Control of Hazardous Air Pollutants From Mobile Sources

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: February 26, 2007 (Volume 72, Number 37)]
[Rules and Regulations]
[Page 8427-8476]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26fe07-19]
[[Page 8428]]

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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 59, 80, 85, and 86
[EPA-HQ-OAR-2005-0036; FRL-8278-4]
RIN 2060-AK70

AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.

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SUMMARY: EPA is adopting controls on gasoline, passenger vehicles, and
portable fuel containers (primarily gas cans) that will significantly
reduce emissions of benzene and other hazardous air pollutants
(``mobile source air toxics''). Benzene is a known human carcinogen,
and mobile sources are responsible for the majority of benzene
emissions. The other mobile source air toxics are known or suspected to
cause cancer or other serious health effects. We are limiting the
benzene content of gasoline to an annual refinery average of 0.62% by
volume, beginning in 2011. In addition, for gasoline, we are
establishing a maximum average standard for refineries of 1.3% by
volume beginning on July 1, 2012, which acts as an upper limit on
gasoline benzene content when credits are used to meet the 0.62 volume
% standard. We are also limiting exhaust emissions of hydrocarbons from
passenger vehicles when they are operated at cold temperatures. This
standard will be phased in from 2010 to 2015. For passenger vehicles,
we are also adopting evaporative emissions standards that are
equivalent to those currently in effect in California. Finally, we are
adopting a hydrocarbon emissions standard for portable fuel containers
beginning in 2009, which will reduce evaporation and spillage of
gasoline from these containers. These controls will significantly
reduce emissions of benzene and other mobile source air toxics such as
1,3-butadiene, formaldehyde, acetaldehyde, acrolein, and naphthalene.
There will be additional substantial benefits to public health and
welfare because of significant reductions in emissions of particulate
matter from passenger vehicles.

DATES: This rule is effective on April 27, 2007.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-HQ-2005-0036. All documents in the docket are listed on the
http://www.regulations.gov Web site. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the Internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically through
http://www.regulations.gov or in hard copy at the Air Docket, EPA/DC,
EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The
Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through
Friday, excluding legal holidays. The telephone number for the Public
Reading Room is (202) 566-1744, and the telephone number for the Air
Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Chris Lieske, U.S. EPA, Office of
Transportation and Air Quality, Assessment and Standards Division
(ASD), Environmental Protection Agency, 2000 Traverwood Drive, Ann
Arbor, MI 48105; telephone number: (734) 214-4584; fax number: (734)
214-4816; e-mail address: lieske.christopher@epa.gov, or Assessment and
Standards Division Hotline; telephone number: (734) 214-4636; e-mail
address: asdinfo@epa.gov.

SUPPLEMENTARY INFORMATION:

Does This Action Apply to Me?

Entities potentially affected by this action are those that produce
new motor vehicles, alter individual imported motor vehicles to address
U.S. regulation, or convert motor vehicles to use alternative fuels. It
will also affect you if you produce gasoline motor fuel or manufacture
portable gasoline containers. Regulated categories include:

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NAICS codes SIC codes
Category \a\ \b\ Examples of potentially affected entities
----------------------------------------------------------------------------------------------------------------
Industry....................... 336111 3711 Motor vehicle manufacturers.
Industry....................... 335312 3621 Alternative fuel vehicle converters.
424720 5172
811198 7539
........... 7549
Industry....................... 811111 7538 Independent commercial importers.
811112 7533
811198 7549
Industry....................... 324110 2911 Gasoline fuel refiners.
Industry....................... 326199 3089 Portable fuel container manufacturers.
332431 3411
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\a\ North American Industry Classification System (NAICS).
\b\ Standard Industrial Classification (SIC) system code.

This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in the table could also be regulated. To determine whether
your activities are regulated by this action, you should carefully
examine the applicability criteria in 40 CFR parts 59, 80, 85, and 86.
If you have any questions regarding the applicability of this action to
a particular entity, consult the person listed in the preceding FOR
FURTHER INFORMATION CONTACT section.

Outline of This Preamble

I. Summary
II. Overview of Final Rule
A. Light-Duty Vehicle Emission Standards
B. Gasoline Fuel Standards
C. Portable Fuel Container (PFC) Controls
III. Why Is EPA Taking This Action?
A. Statutory Requirements
1. Clean Air Act Section 202(l)
2. Clean Air Act Section 183(e)
3. Energy Policy Act
B. Public Health Impacts of Mobile Source Air Toxics (MSATs)
1. What Are MSATs?
2. Health Risk Associated With MSATs
a. National Cancer Risk
b. National Risk of Noncancer Health Effects
c. Exposure Near Roads
d. Exposure From Attached Garages

[[Page 8429]]

3. What Are the Health Effects of Air Toxics?
a. Overview of Potential Cancer and Noncancer Health Effects
b. Health Effects of Key MSATs
i. Benzene
ii. 1,3-Butadiene
iii. Formaldehyde
iv. Acetaldehyde
v. Acrolein
vi. Polycyclic Organic Matter (POM)
vii. Naphthalene
viii. Diesel Exhaust
c. Gasoline PM
d. Near-Roadway Health Effects
C. Ozone
1. Background
2. Health Effects of Ozone
3. Plant and Ecosystem Effects of Ozone
4. Current and Projected 8-hour Ozone Levels
D. Particulate Matter
1. Background
2. Health Effects of PM
3. Welfare Effects of PM
a. Visibility
i. Background
ii Current Visibility Impairment
iii. Future Visibility Impairment
b. Atmospheric Deposition
c. Materials Damage and Soiling
4. Current and Projected PM_2.5 Levels
5. Current PM₁₀ Levels
IV. What Are the Emissions, Air Quality, and Public Health Impacts
of This Rule?
A. Emissions Impacts of All Rule Provisions Combined
1. How Will MSAT Emissions Be Reduced?
2. How Will VOC Emissions Be Reduced?
3. How Will PM Emissions Be Reduced?
B. Emission Impacts by Provision
1. Vehicle Controls
a. Volatile Organic Compounds (VOC)
b. Toxics
c. PM_2.5
2. Fuel Benzene Standard
3. PFC Standards
a. VOC
b. Toxics
C. What Are the Air Quality, Exposure, and Public Health Impacts
of This Rule?
1. Mobile Source Air Toxics
2. Ozone
3. PM
D. What Other Mobile Source Emissions Control Programs Reduce MSATs?
1. Fuels Programs
a. Gasoline Sulfur
b. Gasoline Volatility
c. Diesel Fuel
d. Phase-Out of Lead in Gasoline
2. Highway Vehicle and Engine Programs
3. Nonroad Engine Programs
4. Voluntary Programs
5. Additional Programs Under Development That Will Reduce MSATs
a. On-Board Diagnostics for Heavy-Duty Vehicles Over 14,000 Pounds
b. Standards for Small Nonroad Spark-Ignition Engines
c. Standards for Locomotive and Marine Diesel Engines
E. How Do These Mobile Source Programs Satisfy the Requirements
of Clean Air Act Section 202(l)?
V. New Light-duty Vehicle Standards
A. Introduction
B. What Cold Temperature Requirements Are We Adopting?
1. Why Are We Adopting a New Cold Temperature NMHC Standard?
2. What Are the New NMHC Exhaust Emissions Standards?
3. Feasibility of the Cold Temperature NMHC Standards
a. Currently Available Emission Control Technologies
b. Feasibility Considering Current Certification Levels,
Deterioration and Compliance Margin
c. Feasibility and Test Programs
4. Standards Timing and Phase-In
a. Phase-In Schedule
b. Alternative Phase-In Schedules
5. Certification Levels
6. Credit Program
a. How Credits Are Calculated
b. Credits Earned Prior to Primary Phase-In Schedule
c. How Credits Can Be Used
d. Discounting and Unlimited Life
e. Deficits Can Be Carried Forward
f. Voluntary Heavy-Duty Vehicle Credit Program
7. Additional Vehicle Cold Temperature Standard Provisions
a. Applicability
b. Useful Life
c. High Altitude
d. In-Use Standards for Vehicles Produced During Phase-In
8. Monitoring and Enforcement
C. What Evaporative Emissions Standards Are We Finalizing?
1. Current Controls and Feasibility of the New Standards
2. Evaporative Standards Timing
3. Timing for Flex Fuel Vehicles
4. In-Use Evaporative Emission Standards
5. Existing Differences Between California and Federal
Evaporative Emission Test Procedures
D. Additional Exhaust Control Under Normal Conditions
E. Vehicle Provisions for Small Volume Manufacturers
1. Lead Time Transition Provisions
2. Hardship Provisions
3. Special Provisions for Independent Commercial Importers (ICIs)
VI. Gasoline Benzene Control Program
A. Description of and Rationale for the Gasoline Benzene Control
Program
1. Gasoline Benzene Content Standard
a. Description of the Average Benzene Content Standard
b. Why Are We Finalizing a Benzene Content Standard?
i. Standards That Would Include Toxics Other Than Benzene
ii. Control of Gasoline Sulfur and/or Volatility for MSAT Reduction
iii. Diesel Fuel Changes
c. Why Are We Finalizing a Level of 0.62 vol% for the Average
Benzene Standard?
i. General Technological Feasibility of Benzene Control
ii. Appropriateness of the 0.62 vol% Average Benzene Content Standard
iii. Timing of the Average Standard
d. Upper Limit Benzene Standard
2. Description of the Averaging, Banking, and Trading (ABT) Program
a. Overview
b. Credit Generation
i. Eligibility
ii. Early Credit Generation
iii. Standard Credit Generation
c. Credit Use
i. Early Credit Life
ii. Standard Credit Life
iii. Consideration of Unlimited Credit Life
iv. Credit Trading Provisions
3. Provisions for Small Refiners and Refiners Facing Hardship
Situations
a. Provisions for Small Refiners
i. Definition of Small Refiner for Purposes of the MSAT2 Small
Refiner Provisions
ii. Small Refiner Status Application Requirements
iii. Small Refiner Provisions
iv. The Effect of Financial and Other Transactions on Small
Refiner Status and Small Refiner Relief Provisions
b. Provisions for Refiners Facing Hardship Situations
i. Temporary Waivers Based on Extreme Hardship Circumstances
ii. Temporary Waivers Based on Unforeseen Circumstances
c. Option for Early Compliance in Certain Circumstances
B. How Will the Gasoline Benzene Standard Be Implemented?
1. General Provisions
2. Small Refiner Status Application Requirements
3. Administrative and Enforcement Provisions
a. Sampling/Testing
b. Recordkeeping/Reporting
C. How Will the Program Relate to Other Fuel-Related Toxics Programs?
D. How Does This Program Satisfy the Statutory Requirements of
Clean Air Act Section 202(l)(2)?
VII. Portable Fuel Containers
A. What Are the New HC Emissions Standards for PFCs?
1. Description of Emissions Standard
2. Determination of Best Available Control
3. Diesel, Kerosene and Utility Containers
4. Automatic Shut-Off
B. Timing of Standard
C. What Test Procedures Would Be Used?
1. Diurnal Test
2. Preconditioning To Ensure Durable In-Use Control
a. Durability Cycles
b. Preconditioning Fuel Soak
c. Spout Actuation
D. What Certification and In-Use Compliance Provisions Is EPA Adopting?
1. Certification
2. Emissions Warranty and In-Use Compliance
3. Labeling
E. How Would State Programs Be Affected by EPA Standards?
F. Provisions for Small PFC Manufacturers
1. First Type of Hardship Provision
2. Second Type of Hardship Provision
VIII. What Are the Estimated Impacts of the Rule?
A. Refinery Costs of Gasoline Benzene Reduction
1. Methodology
a. Overview of the Benzene Program Cost Methodology

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b. Changes to the Cost Estimation Methodology Used in the
Proposed Rule
c. Linear Programming Cost Model
d. Refinery-by-Refinery Cost Model
e. Price of Chemical Grade Benzene
2. Summary of Costs
a. Nationwide Costs of the Final Benzene Control Program
b. Regional Costs
c. Refining Industry Cost Study
B. What Are the Vehicle Cost Impacts?
C. What Are the PFC Cost Impacts?
D. Cost per Ton of Emissions Reduced
E. Benefits
1. Unquantified Health and Environmental Benefits
2. Quantified Human Health and Environmental Effects of the
Final Cold Temperature Vehicle Standard
3. Monetized Benefits
4. What Are the Significant Limitations of the Benefit Analysis?
5. How Do the Benefits Compare to the Costs of the Final Standards?
F. Economic Impact Analysis
1. What Is an Economic Impact Analysis?
2. What Is the Economic Impact Model?
3. What Economic Sectors Are Included in This Economic Impact Analysis?
4. What Are the Key Features of the Economic Impact Model?
5. What Are the Key Model Inputs?
6. What Are the Results of the Economic Impact Modeling?
IX. Public Participation
X. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act (RFA), as Amended by the Small
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5
U.S.C. 601 et seq.
1. Overview
2. The Need for and Objectives of This Rule
3. Summary of the Significant Issues Raised by the Public Comments
4. Summary of Regulated Small Entities
a. Highway Light-Duty Vehicles
b. Gasoline Refiners
c. Portable Fuel Container Manufacturers
5. Description of the Reporting, Recordkeeping, and Other
Compliance Requirements of the Rule
6. Relevant Federal Rules
7. Steps Taken To Minimize the Significant Economic Impact on
Small Entities
a. Significant Panel Findings
b. Outreach With Small Entities (and the Panel Process)
c. Small Business Flexibilities
i. Highway Light-Duty Vehicles
ii. Gasoline Refiners
iii. Portable Fuel Containers
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer Advancement Act
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income Populations
K. Congressional Review Act
XI. Statutory Provisions and Legal Authority

I. Summary

Mobile sources emit air toxics (also known as ``hazardous air
pollutants'') that can cause cancer and other serious health effects.
Mobile sources contribute significantly to the nationwide risk from
breathing outdoor sources of air toxics. Mobile sources were
responsible for about 44% of outdoor toxic emissions, almost 50% of the
cancer risk, and 74% of the noncancer risk according to EPA's National-
Scale Air Toxics Assessment (NATA) for 1999. In addition, people who
live or work near major roads or live in homes with attached garages
are likely to have higher exposures and risk, which are not reflected
in NATA.
According to NATA for 1999, there are a few mobile source air
toxics that pose the greatest risk based on current information about
ambient levels and exposure. These include benzene, 1,3-butadiene,
formaldehyde, acrolein, naphthalene, and polycyclic organic matter
(POM). All of these compounds are gas-phase hydrocarbons except POM,
which appears in the gas and particle phases. Benzene is the most
significant contributor to cancer risk from all outdoor air toxics,
according to NATA for 1999. NATA does not include a quantitative
estimate of cancer risk for diesel exhaust, but it concludes that
diesel exhaust is a mixture of pollutants that collectively poses one
of the greatest relative cancer risks when compared with the other
individual pollutants assessed. Although we expect significant
reductions in mobile source air toxics in the future, cancer and
noncancer health risks will remain a public health concern, and
exposure to benzene will remain the largest contributor to this risk.
In this rule, we are finalizing standards for passenger vehicles,
gasoline, and portable fuel containers (typically gas cans).
Specifically, we are finalizing standards for:
? exhaust hydrocarbon emissions from passenger vehicles
during cold temperature operation;
? evaporative hydrocarbon emissions from passenger vehicles;
? the benzene content of gasoline; and
? hydrocarbon emissions from portable fuel containers that
would reduce evaporation, permeation, and spillage from these containers.
These standards will significantly reduce emissions of the many air
toxics that are hydrocarbons, including benzene, 1,3-butadiene,
formaldehyde, acetaldehyde, acrolein, and naphthalene. The fuel benzene
standards and hydrocarbon standards for vehicles and portable fuel
containers will together reduce total emissions of air toxics by
330,000 tons in 2030, including 61,000 tons of benzene. As a result of
this final rule, in 2030 passenger vehicles will emit 45% less benzene,
gas cans will emit almost 80% less benzene, and gasoline will have 38%
less benzene overall. Mobile sources were responsible for over 70% of
benzene emissions in 1999.
The reductions in mobile source air toxics emissions will reduce
exposure and predicted risk of cancer and noncancer health effects,
including in environments where exposure and risk may be highest, such
as near roads, in vehicles, and in homes with attached garages.
Nationwide, the cancer risk attributable to total MSATs emitted by all
mobile sources will be reduced by 30%, and the risk from mobile source
benzene will be reduced by 37%. At 2030 exposure levels, the highway
vehicle contribution to MSAT cancer risk will be reduced on average 36%
across the U.S., and the highway vehicle contribution to benzene cancer
risk will be reduced on average by 43% across the U.S. Nationwide, the
mobile source contribution to the respiratory hazard index will be
reduced by 23%. In addition, the hydrocarbon reductions from the
vehicle and gas can standards will reduce VOC emissions (which are
precursors to ozone and PM_2.5) by over 1.1 million tons in
2030. The vehicle standards will reduce direct PM_2.5
emissions by over 19,000 tons in 2030 and will also reduce secondary
formation of PM_2.5. Although ozone and PM_2.5 are
considered criteria pollutants rather than ``air toxics,'' reductions
in ozone and PM_2.5 are nevertheless important co-benefits of
this proposal.
Section I.B.2 of this preamble provides more discussion of the
public health and environmental impacts of mobile source air toxics,
ozone, and PM. Details on health effects, emissions, exposure, and
cancer risks are also located in Chapters 1-3 of the Regulatory Impact
Analysis (RIA) for this rule.
We estimate that the benefits of this rule will be about $6 billion
in 2030, based on the direct PM_2.5 reductions from the
vehicle standards, plus unquantified benefits from reductions in mobile
source air toxics and VOC. We estimate that the annual net social costs
of this rule will be about $400 million

[[Page 8431]]

in 2030 (expressed in 2003 dollars). These net social costs include the
value of fuel savings from the proposed gas can standards, which will
be worth about $92 million in 2030.
The rule will have an average cost of 0.27 cents per gallon of
gasoline, less than $1 per vehicle, and less than $2 per gas can. The
reduced evaporation from gas cans will result in fuel savings that will
more than offset the increased cost for the gas can. In 2030, the long-
term cost per ton of the standards (in combination, and including fuel
savings) will be $1,100 per ton of total mobile source air toxics
reduced; $5,900 per ton of benzene reduced; and no cost for the
hydrocarbon and PM reductions (because we expect the vehicle standards
will have no cost in 2020 and beyond). Section VIII of the preamble and
Chapters 8-13 of the RIA provide more details on the costs, benefits,
and economic impacts of the standards. The impacts on small entities
and the flexibilities we are finalizing are discussed in section X of
this preamble and Chapter 14 of the RIA.

II. Overview of Final Rule

A. Light-Duty Vehicle Emission Standards

As described in more detail in section V, we are adopting new
standards for both exhaust and evaporative emissions from passenger
vehicles. The new exhaust emissions standards will significantly reduce
non-methane hydrocarbon (NMHC) emissions from passenger vehicles at
cold temperatures. These hydrocarbons include many mobile source air
toxics (including benzene), as well as VOC.
As we discussed in the proposal, current vehicle emission standards
are based on testing of NMHC that is generally performed at 75 [deg]F.
Recent research and analysis indicates that these standards are not
resulting in robust control of NMHC at lower temperatures. We believe
that cold temperature NMHC control can be substantially improved using
the same technological approaches that are generally already being used
in the Tier 2 vehicle fleet to meet the stringent standards at 75
[deg]F. These cold-temperature NMHC controls will also result in lower
direct PM emissions at cold temperatures.
Accordingly, consistent with the proposal, we are adopting a new
NMHC exhaust emissions standard at 20 [deg]F for light-duty vehicles,
light-duty trucks, and medium-duty passenger vehicles. Vehicles at or
below 6,000 pounds gross vehicle weight rating (GVWR) will be subject
to a sales-weighted fleet average NMHC level of 0.3 grams/mile.
Vehicles between 6,000 and 8,500 pounds GVWR and medium-duty passenger
vehicles will be subject to a sales-weighted fleet average NMHC level
of 0.5 grams/mile. For lighter vehicles, the standard will phase in
between 2010 and 2013. For heavier vehicles, the new standards will
phase in between 2012 and 2015. The standards include a credit program
and other provisions designed to provide flexibility to manufacturers,
especially during the phase-in periods. These provisions are designed
to allow the earliest possible phase-in of standards and help minimize
costs and ease the transition to new standards. These standards in
combination are expected to lead to emissions control over a wide range
of in-use temperatures, and not just at 20 [deg]F and 75 [deg]F.
We are also establishing, as proposed, a set of nominally more
stringent evaporative emission standards for all light-duty vehicles,
light-duty trucks, and medium-duty passenger vehicles. The standards
are equivalent to California's Low Emission Vehicle II (LEV II)
standards, and they reflect the evaporative emissions levels that are
already being achieved nationwide. The standards codify the approach
that most manufacturers are already taking for 50-state evaporative
systems, and thus prevent backsliding in the future. The evaporative
emission standards will take effect in 2009 for lighter vehicles and in
2010 for the heavier vehicles.
Section V of this preamble provides details on the exhaust and
evaporative vehicle standards.

B. Gasoline Fuel Standards

As we proposed, we are limiting the benzene content of all
gasoline, both reformulated and conventional. Beginning January 1,
2011, refiners must meet a refinery average gasoline benzene content
standard of 0.62% by volume on all their gasoline. The program is
described in more detail in section VI of this preamble. The standard
does not apply to gasoline produced and/or sold for use in California
because such gasoline is already covered under California's Phase 3
Reformulated Gasoline (Ca3RFG) program.
The benzene content standard, in combination with the existing
gasoline sulfur standard, will result in air toxics emissions
reductions that are greater than required under all existing gasoline
toxics programs. As a result, upon full implementation in 2011, the
regulatory provisions for the benzene control program will become the
regulatory mechanism used to implement the reformulated gasoline (RFG)
and Anti-dumping annual average toxics performance and benzene content
requirements. The current RFG and Anti-dumping annual average
provisions thus will be replaced by this benzene control program. This
benzene control program will also replace the requirements of the 2001
MSAT rule (``MSAT1''). In addition, the program will satisfy certain
fuel MSAT conditions of the Energy Policy Act of 2005 and obviate the
need to revise toxics baselines for reformulated gasoline otherwise
required by that Act. In all of these ways, the existing national fuel-
related MSAT regulatory program will be significantly consolidated and
simplified.
We are finalizing a nationwide ABT program that allows refiners and
importers to choose the most economical compliance strategy (investment
in technology, credits, or both) for meeting the 0.62 vol% annual
average standard. From 2007-2010, refiners can generate ``early
credits'' by making qualifying benzene reductions earlier than
required. Beginning in 2011 and continuing indefinitely, refiners and
importers can generate ``standard credits'' by producing/importing
gasoline with benzene levels below 0.62 volume percent (vol%) on an
annual average basis. Credits may be used interchangeably towards
company compliance with the 0.62 vol% standard, ``banked'' for future
use, and/or transferred nationwide to other refiners/importers subject
to the standard. In addition to the 0.62 vol% standard, refiners and
importers must also meet a 1.3 vol% maximum average benzene standard
beginning July 1, 2012. To comply with the maximum average standard,
gasoline produced by a refinery or imported by an importer may not
exceed 1.3 vol% benzene on an annual average basis.
The ABT program allows us to set a numerically more stringent
benzene standard than would otherwise be achievable (within the meaning
of Clean Air Act section 202(l)(2)). The ABT program also allows
implementation to occur earlier. Under this benzene content standard
and ABT program, gasoline in all areas of the country will have lower
benzene levels than they have today. Overall benzene levels will be 38%
lower. This will reduce benzene emissions and exposure nationwide.
The program includes special provisions for refiners facing
hardship. Refiners approved as ``small refiners'' are eligible for
certain temporary relief provisions. In addition, any refiner facing
extreme unforeseen circumstances or extreme hardship

[[Page 8432]]

circumstances can apply for similar temporary relief.

C. Portable Fuel Container (PFC) Controls

Portable fuel containers, such as gas cans and diesel and kerosene
containers, are consumer products used to refuel a wide variety of
equipment, including lawn and garden equipment, recreational equipment,
and passenger vehicles that have run out of gas. As described in
section VII, we are adopting standards for these containers that would
reduce hydrocarbon emissions from evaporation, permeation, and
spillage. The program we are finalizing is consistent with the
proposal, except that instead of applying only to gasoline containers,
it will also apply to diesel and kerosene containers. These standards
will significantly reduce emissions of benzene and other gaseous
toxics, as well as VOC. VOC is an ozone precursor, and certain aromatic
species are believed to contribute to secondary organic PM _2.5.
We are finalizing a performance-based standard of 0.3 grams per
gallon per day of hydrocarbons, determined based on the emissions from
the can over a diurnal test cycle specified in the rule. The standard
applies to containers manufactured on or after January 1, 2009. We are
also establishing test procedures and a certification and compliance
program, in order to ensure that containers meet the emission standard
over a range of in-use conditions. The standards are based on the
performance of best available control technologies, such as durable
permeation barriers, automatically closing spouts, and cans that are
well-sealed, and the standards will result in the use of these control
technologies.
California implemented an emissions control program for gas cans in
2001, and since then, several other states have adopted the program.
Last year, California adopted a revised program, which will take effect
July 1, 2007. The revised California program is very similar to the
program we are finalizing. Although a few aspects of the programs are
different, we believe manufacturers will be able to meet both EPA and
California requirements with the same container designs, resulting in
equivalent emission reductions.

III. Why Is EPA Taking This Action?

People experience elevated risk of cancer and other noncancer
health effects from exposure to air toxics. Mobile sources are
responsible for a significant portion of this risk. For example,
benzene is the most significant contributor to cancer risk from all
outdoor air toxics \1\, and most of the nation's benzene emissions come
from mobile sources. These risks vary depending on where people live
and work and the kinds of activities in which they engage. People who
live or work near major roads, people that spend a large amount of time
in vehicles or work with motorized equipment, and people living in
homes with attached garages are likely to have higher exposures and
higher risks. Although we expect significant reductions in mobile
source air toxics in the future, predicted cancer and noncancer health
risks are likely to remain a public health concern. Benzene will likely
remain the largest contributor to this risk. In addition, some mobile
source air toxics contribute to the formation of ozone and PM
_2.5, which contribute to serious public health problems.
Section III.B of this preamble discusses the risks posed by outdoor
toxics now and in the future. Sections III.C and III.D discuss the
health and welfare effects of ozone and PM, respectively. The controls
in this rule will significantly reduce exposure to emissions of mobile
source air toxics (and reduce exposure to ozone and PM _2.5
as well), thus reducing these public health concerns.
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\1\ Based on quantitative estimates of risk, which do not
include risks associated with diesel particulate matter and diesel
exhaust organic gases.
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A. Statutory Requirements

1. Clean Air Act Section 202(l)
Section 202(l)(2) of the Clean Air Act requires EPA to set
standards to control hazardous air pollutants (``air toxics'') from
motor vehicles \2\, motor vehicle fuels, or both. These standards must
reflect the greatest degree of emission reduction achievable through
the application of technology which will be available, taking into
consideration the motor vehicle standards established under section
202(a) of the Act, the availability and cost of the technology, and
noise, energy and safety factors, and lead time. The standards are to
be set under Clean Air Act sections 202(a)(1) or 211(c)(1), and they
are to apply, at a minimum, to benzene and formaldehyde emissions.
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\2\ ``Motor vehicles'' is a term of art, defined in Clean Air
Act section 216(2) as ``any self-propelled vehicle designed for
transporting persons or property on a street or highway.''
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Section 202(a)(1) of the Clean Air Act directs EPA to set standards
for new motor vehicles or new motor vehicle engines which EPA judges to
cause or contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare. We are issuing the
vehicle emissions standards under this authority in conjunction with
section 202(l)(2).
Section 211(c)(1)(A) of the Clean Air Act authorizes EPA (among
other things) to control the manufacture of fuel if any emission
product of such fuel causes or contributes to air pollution which may
reasonably be anticipated to endanger public health or welfare. We are
issuing the benzene standard for gasoline under this authority in
conjunction with section 202(l)(2).
Clean Air Act section 202(l)(2) also requires EPA to revise its
regulations controlling hazardous air pollutants from motor vehicles
and fuels, ``from time to time.'' EPA's first rule under Clean Air Act
section 202(l) was published on March 29, 2001, entitled, ``Control of
Emissions of Hazardous Air Pollutants from Mobile Sources'' (66 FR
17230). That rule committed to additional rulemaking that would
evaluate the need for and feasibility of additional controls. Today's
final rule fulfills that commitment.
2. Clean Air Act Section 183(e)
Clean Air Act section 183(e)(3) requires EPA to list categories of
consumer or commercial products that the Administrator determines,
based on an EPA study of VOC emissions from such products, contribute
at least 80 percent of the VOC emissions from such products in areas
violating the national ambient air quality standard for ozone. EPA
promulgated this list at 60 FR 15264 (March 23, 1995), but it did not
consider or list portable fuel containers. After analyzing these
containers' emissions inventory impacts, we recently published a
Federal Register notice that added portable fuel containers to the list
of consumer products to be regulated.\3\ EPA is required to develop
rules reflecting ``best available controls'' to reduce VOC emissions
from the listed products. ``Best available controls'' are defined in
section 183(e)(1)(A) as follows:
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\3\ 71 FR 28320, May 16, 2006, ``Consumer and Commercial
Products: Schedule for Regulation''.

The term ``best available controls'' means the degree of
emissions reduction that the Administrator determines, on the basis
of technological and economic feasibility, health, environmental,
and energy impacts, is achievable through the application of the
most effective equipment, measures, processes, methods, systems, or
techniques, including chemical reformulation, product or feedstock
substitution, repackaging, and directions for use, consumption,
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storage, or disposal.

Section 183(e)(4) also allows these standards to be implemented by
means

[[Page 8433]]

of ``any system or systems of regulation as the Administrator may deem
appropriate, including requirements for registration and labeling,
self-monitoring and reporting * * * concerning the manufacture,
processing, distribution, use, consumption, or disposal of the
product.'' We are issuing a hydrocarbon standard for portable fuel
containers under the authority of section 183(e).
3. Energy Policy Act
Section 1504(b) of the Energy Policy Act of 2005 requires EPA to
adjust the toxics emissions baselines for individual refineries for
reformulated gasoline to reflect 2001-2002 fuel qualities. However, the
Act provides that this action becomes unnecessary if EPA takes action
which results in greater overall reductions of toxics emissions from
vehicles in areas with reformulated gasoline. As described in section
VI of this preamble, we believe the benzene content standard we are
finalizing today will in fact result in greater overall reductions than
would be achieved by adjusting the individual baselines under the
Energy Policy Act. Accordingly, under the provisions of the Energy
Policy Act, this rule obviates the need for readjusting emissions
baselines for reformulated gasoline.

B. Public Health Impacts of Mobile Source Air Toxics (MSATs)

1. What Are MSATs?
Section 202(l) refers to ``hazardous air pollutants from motor
vehicles and motor vehicle fuels.'' We use the term ``mobile source air
toxics (MSATs)'' to refer to compounds that are emitted by mobile
sources and have the potential for serious adverse health effects. Some
MSATs are known or suspected to cause cancer. Some of these pollutants
are also known to have adverse health effects on people's respiratory,
cardiovascular, neurological, immune, reproductive, or other organ
systems, and they may also have developmental effects. Some may pose
particular hazards to more susceptible and sensitive populations, such
as pregnant women, children, the elderly, or people with pre-existing
illnesses.
Some MSATs of particular concern include benzene, 1,3-butadiene,
formaldehyde, acrolein, naphthalene, polycyclic organic matter, and
diesel particulate matter and diesel exhaust organic gases. These are
compounds that EPA's National-Scale Air Toxics Assessment (NATA) for
1999 \4\ identifies as the most significant contributors to cancer and
noncancer health risk from breathing outdoor air toxics, and that have
a significant contribution from mobile sources. Our understanding of
what compounds pose the greatest risk will evolve over time, based on
our understanding of the ambient levels and health effects associated
with the compounds.
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\4\ http://www.epa.gov/ttn/atw/nata1999/.

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EPA has compiled a Master List of Compounds Emitted by Mobile
Sources, based on an extensive review of the literature on exhaust and
evaporative emissions from onroad and nonroad equipment. The list
currently includes approximately 1,000 compounds, and it is available
in the public docket for this rule and on the Web (http://www.epa.gov/otaq/
toxics.htm). Chapter 1 of the RIA provides a detailed discussion
of information sources for identifying those compounds that have the
potential for serious adverse health effects (i.e., could be considered
``MSATs''). This discussion includes a list of those compounds that are
emitted by mobile sources and listed in EPA's Integrated Risk
Information System (IRIS).
MSATs are emitted by motor vehicles, nonroad engines (such as lawn
and garden equipment, farming and construction equipment, locomotives,
and ships), aircraft, and their fuels. MSATs are emitted as a result of
various processes. Some MSATs are present in fuel or fuel additives and
are emitted to the air when the fuel evaporates or passes through the
engine. Some MSATs are formed through engine combustion processes. Some
compounds, like formaldehyde and acetaldehyde, are also formed through
a secondary process when other mobile source pollutants undergo
chemical reactions in the atmosphere. Finally, some air toxics, such as
metals, result from engine wear or from impurities in oil or fuel.
There are other sources of air toxics, including stationary
sources, such as power plants, factories, oil refineries, dry cleaners,
gas stations, and small manufacturers. They can also be produced by
combustion of wood and other organic materials. There are also indoor
sources of air toxics, such as solvent evaporation and outgassing from
furniture and building materials.
2. Health Risk Associated With MSATs
EPA's National-Scale Air Toxics Assessment (NATA) for 1999 provides
some perspective on the average risk of cancer and noncancer health
effects associated with breathing air toxics from outdoor sources, and
the contribution of mobile sources to these risks.5, 6 NATA
assessed 177 pollutants. It is worth noting that NATA does not include
indoor sources of air toxics. Also, it assumes uniform outdoor
concentrations within a census tract, and therefore does not reflect
elevated concentrations and exposures near roadways or other sources
within a census tract. Additional limitations and uncertainties
associated with NATA are discussed in Section 3.2.1.3 of the RIA.
Nevertheless, its findings are useful in providing a perspective on the
magnitude of risks posed by outdoor sources of air toxics generally,
and in identifying what pollutants and sources are important
contributors to these health risks. Some of NATA's findings are
discussed in the paragraphs below.
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\5\ http://www.epa.gov/ttn/atw/nata1999/.
\6\ NATA does not include a quantitative estimate of cancer risk
for diesel particulate matter and diesel exhaust organic gases. EPA
has concluded that while diesel exhaust is likely to be a human
carcinogen, available data are not sufficient to develop a confident
estimate of cancer unit risk.
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For this rule, EPA also performed a national-scale assessment for
1999 and future years using the same modeling tools and approach as the
1999 NATA, but with updated emissions inventories and an updated
exposure model. The exposure model accounts for higher toxics
concentrations near roads. This updated national-scale analysis
examined only those toxics that are emitted by mobile sources (i.e., a
subset of the 177 pollutants included in NATA). However, the analysis
includes all sources of those pollutants, including mobile, stationary,
and area sources. The analysis is discussed in detail in Chapter 3 of
the RIA, and some highlights of the findings are discussed immediately
below.
In addition to national-scale analysis, we have also evaluated more
refined local-scale modeling, measured ambient concentrations, personal
exposure measurements, and other data. This information is discussed in
detail in Chapter 3 of the RIA. These data collectively show that while
levels of air toxics are decreasing, potential public health risks
remain a concern, and ambient levels and personal exposure vary
significantly. These data indicate that concentrations of benzene and
other air toxics can be higher near high-traffic roads, inside
vehicles, and in homes with attached garages.
a. National Cancer Risk
According to NATA, the average national cancer risk in 1999 from
all outdoor sources of air toxics was estimated to be 42 in a million.
That is, 42 out of one million people would be

[[Page 8434]]

expected to contract cancer from a lifetime of breathing air toxics at
1999 levels. Mobile sources were responsible for 44% of outdoor toxic
emissions and almost 50% of the cancer risk. Benzene is the largest
contributor to cancer risk of all 133 pollutants quantitatively
assessed in the 1999 NATA, and mobile sources are the single largest
source of ambient benzene.
According to the national-scale analysis performed for this rule,
the national average cancer risk in 1999 from breathing outdoor sources
of MSATs was about 25 in a million.\7\ Over 224 million people in 1999
were exposed to a risk level above 10 in a million due to chronic
inhalation exposure to MSATs. About 130 million people in 1999 were
exposed to a risk level above 10 in a million due to chronic inhalation
exposure to benzene alone. Mobile sources were responsible for over 70%
of benzene emissions in 1999.
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\7\ This includes emissions from mobile and stationary sources
of these pollutants.
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Although air toxics emissions are projected to decline in the
future as a result of standards EPA has previously adopted, cancer risk
will continue to be a public health concern. Without additional
controls, the predicted national average cancer risk from MSATs in 2030
is predicted to be above 20 in a million. In fact, in 2030 there will
be more people exposed to levels of MSATs that result in the highest
levels of risk. For instance, the number of Americans above the 10 in a
million cancer risk level from exposure to MSATs is projected to
increase from 223 million in 1999 to 272 million in 2030. Mobile
sources will continue to be a significant contributor to risk in the
future, accounting for 43% of total air toxic emissions in 2020, and
55% of benzene emissions.
b. National Risk of Noncancer Health Effects
According to national-scale modeling for 1999 done for this rule,
nearly the entire U.S. population was exposed to an average level of
air toxics that has the potential for adverse respiratory health
effects (noncancer).\8\ We estimated this will continue to be the case
in 2030, even though toxics levels will be lower.
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\8\ That is, the respiratory hazard index exceeded 1. See
section III.B.3.a for more information.
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Mobile sources were responsible for 74% of the noncancer
(respiratory) risk from outdoor air toxics in the 1999 NATA. The
majority of this risk was from acrolein, and formaldehyde also
contributed to the risk of respiratory health effects.\9\
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\9\ Acrolein was assigned an overall confidence level of
``lower'' based on consideration of the combined uncertainties from
the modeling estimates. In contrast, formaldehyde was assigned an
overall confidence level of ``medium.''
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Although not included in NATA's estimates of noncancer risk, PM
from gasoline and diesel mobile sources contributes significantly to
the health effects associated with ambient PM, for which EPA has
established National Ambient Air Quality Standards. There are extensive
human data showing a wide spectrum of adverse health effects associated
with exposure to ambient PM.\10\
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\10\ U.S. Environmental Protection Agency (2004) Air Quality
Criteria for Particulate Matter. Research Triangle Park, NC:
National Center for Environmental Assessment--RTP Office; Report No.
EPA/600/P-99/002aF, p. 8-318.
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c. Exposure Near Roads
A substantial number of modeling assessment and air quality
monitoring studies show elevated concentrations of multiple MSATs in
close proximity to major roads. Exposure studies also indicate that
populations spending time near major roadways likely experience
elevated personal exposures to motor vehicle-related pollutants. In
addition, these populations may experience exposures to differing
physical and chemical compositions of certain air toxic pollutants
depending on the amount of time spent in close proximity to motor
vehicle emissions. Chapter 3.1 of the RIA provides a detailed
discussion of air quality monitoring, personal exposure monitoring, and
modeling assessments near major roadways.
As part of the analyses underlying the final rule, we employed a
new version of the Hazardous Air Pollutant Exposure Model (HAPEM), the
exposure model used in NATA. HAPEM6 explicitly accounts for the
gradient in outdoor concentrations that occurs near major roads, and
the fraction of the population living near major roads.\11\ The HAPEM6
analysis highlights the fact that residence near a major road is a
substantial contributor to overall differences in exposure to directly-
emitted MSATs. As an example, while the average of within-tract median
annual census tract exposure concentrations nationally is 1.4 [mu]g/
m3, the average 90th percentile of within-tract exposure
concentration nationally is over 2 [mu]g/m3.
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\11\ U.S. EPA. 2007. The HAPEM6 User's Guide. Prepared for Ted
Palma, Office of Air Quality Planning and Standards, Research
Triangle Park, NC, by Arlene Rosenbaum and Michael Huang, ICF
International, January 2007. This document is available in Docket
EPA-HQ-OAR-2005-0036. http://www.epa.gov/ttn/fera/human_hapem.html.

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The potential population exposed to elevated concentrations near
major roadways is large. A study of the populations nationally
indicated that more than half of the population lives within 200 meters
of a major road.\12\ It should be noted that this analysis relied on
the Census Bureau definition of a major road, which is not based on
traffic volume. Thus, some of the roads designated as ``major'' may
carry a low volume of traffic. This estimate is consistent with other
studies that have examined the proximity of population to major roads.
These studies are discussed in Section 3.5 of the RIA. In addition,
analysis of data from the Census Bureau's American Housing Survey
suggests that approximately 37 million people live within 300 feet
(~100 meters) of a 4-or-more lane highway, railroad, or airport.\13\
American Housing Survey statistics, as well as epidemiology studies,
indicate that those houses located near major transportation sources
are more likely to be lower in income or have minority residents than
houses not located near major transportation sources. These data are
also discussed in detail in Section 3.5 of the RIA.
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\12\ Major roads are defined as those roads defined by the U.S.
Census as one of the following: ``limited access highway,''
``highway,'' ``major road (primary, secondary and connecting roads
),'' or ``ramp.''
\13\ United States Census Bureau. (2004) American Housing Survey
web page. [Online at
http://www.census.gov/hhes/www/housing/ahs/ahs03/ahs03.html]
Table IA-6.

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Other population studies also indicate that a significant fraction
of the population resides in locations near major roads. At present,
the available studies use different indicators of ``major road'' and of
``proximity,'' but the estimates range from 12.4% of student enrollment
in California attending schools within 150 meters of roads with 25,000
vehicles per day or more, to 13% of Massachusetts veterans living
within 50 meters of a road with at least 10,000 vehicles per
day.14, 15 Using a more general definition of a ``major
road,'' between 22% and 51% of different study populations live near
such roads.
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\14\ Green, R.S.; Smorodinsky, S.; Kim, J.J.; McLaughlin, R.;
Ostro, B. (2004) Proximity of California public schools to busy
roads. Environ. Health Perspect. 112: 61-66.
\15\ Garshick, E.; Laden, F.; Hart, J.E.; Caron, A. (2003)
Residence near a major road and respiratory symptoms in U.S.
veterans. Epidemiol. 14: 728-736.
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d. Exposure From Attached Garages
People living in homes with attached garages are potentially
exposed to substantially higher overall

[[Page 8435]]

concentrations of benzene, toluene, and other VOCs from mobile source-
related emissions. EPA has conducted a modeling analysis to examine the
influence of attached garages on personal exposure to benzene (see
Appendix 3A of RIA). Compared to national average exposure
concentrations modeled in 1999 NATA, which does not account for
emissions originating in attached garages, average exposure
concentrations for people with attached garages could more than double.
Other recent studies also emphasize the substantial role of attached
garages in exposure to MSATs. Chapter 3 of the RIA discusses
measurements of concentrations and exposure associated with attached
garages and EPA's modeling analysis.
3. What Are the Health Effects of Air Toxics?
a. Overview of Potential Cancer and Noncancer Health Effects
Air toxics can cause of variety of cancer and noncancer health
effects. Inhalation cancer risks are usually estimated by EPA as ``unit
risks,'' which represent the excess lifetime cancer risk estimated to
result from continuous exposure to an agent at a concentration of 1 mu
g/m\3\ in air. Some air toxics are known to be carcinogenic in animals
but lack data in humans. Many of these have been assumed to be human
carcinogens. Also, in the absence of evidence of a nonlinear dose-
response curve, EPA assumes these relationships between exposure and
probability of cancer are linear. These unit risks are typically upper
bound estimates. Upper bound estimates are more likely to overestimate
than underestimate risk. Where there are strong epidemiological data, a
maximum likelihood estimate (MLE) may be developed. An MLE is a best
scientific estimate of risk. The benzene unit risk is an MLE. A
discussion of the confidence in a quantitative cancer risk estimate is
provided in the IRIS file for each compound. The discussion of the
confidence in the cancer risk estimate includes an assessment of the
source of the data (human or animal), uncertainties in dose estimates,
choice of the model used to fit the exposure and response data and how
uncertainties and potential confounders are handled.
Potential noncancer chronic inhalation health risks are quantified
using reference concentrations (RfCs) and noncancer chronic ingestion
and dermal health risks are quantified using reference doses (RfDs).
The RfC is an estimate (with uncertainty spanning perhaps an order of
magnitude) of a daily exposure to the human population (including
sensitive subgroups) that is likely to be without appreciable risk of
deleterious effects during a lifetime. Sources of uncertainty in the
development of the RfCs and RfDs include interspecies extrapolation
(animal to human) and intraspecies extrapolation (average human to
sensitive human). Additional sources of uncertainty can include the use
of a lowest observed adverse effect level in place of a no observed
adverse effect level, and other data deficiencies. A statement
regarding the confidence in the RfC and/or RfD is developed to reflect
the confidence in the principal study or studies on which the RfC or
RfD are based and the confidence in the underlying database. Factors
that affect the confidence in the principal study include how well the
study was designed, conducted and reported. Factors that affect the
confidence in the database include an assessment of the availability of
information regarding identification of the critical effect,
potentially susceptible populations and exposure scenarios relevant to
assessment of risk.
The RfC may be used to estimate a hazard quotient, which is the
environmental exposure to a substance divided by its RfC. A hazard
quotient greater than one indicates adverse health effects are
possible. The hazard quotient cannot be translated to a probability
that adverse health effects will occur, and is unlikely to be
proportional to risk. It is especially important to note that a hazard
quotient exceeding one does not necessarily mean that adverse health
effects will occur. In NATA, hazard quotients for different respiratory
irritants were also combined into a hazard index (HI). A hazard index
is the sum of hazard quotients for substances that affect the same
target organ or organ system. Because different pollutants may cause
similar adverse health effects, it is often appropriate to combine
hazard quotients associated with different substances. However, the HI
is only an approximation of a combined effect because substances may
affect a target organ in different ways.
b. Health Effects of Key MSATs
i. Benzene
The EPA's IRIS database lists benzene, an aromatic hydrocarbon, as
a known human carcinogen (causing leukemia) by all routes of
exposure.\16\ A number of adverse noncancer health effects including
blood disorders and immunotoxicity have also been associated with long-
term occupational exposure to benzene.\17\
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\16\ U.S. EPA (2000). Integrated Risk Information System File
for Benzene. This material is available electronically at
http://www.epa.gov/iris/subst/0276.htm.
\17\ U.S. EPA (2002). Toxicological Review of Benzene (Noncancer
Effects). National Center for Environmental Assessment, Washington,
DC. Report No. EPA/635/R-02/001F.
http://www.epa.gov/iris/toxreviews/0276-tr.pdf.

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Inhalation is the major source of human exposure to benzene in
occupational and non-occupational settings. Long-term occupational
inhalation exposure to benzene has been shown to cause cancers of the
hematopoetic (blood cell) system in adults.\18\ Among these are acute
nonlymphocytic leukemia \19\ and chronic lymphocytic
leukemia.20, 21 Leukemias, lymphomas, and other tumor types
have been observed in experimental animals exposed to benzene by
inhalation or oral administration. Exposure to benzene and/or its
metabolites has also been linked with chromosomal changes in

[[Page 8436]]

humans and animals22, 23 and increased proliferation of
mouse bone marrow cells.24, 25
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\18\ U.S. EPA (1998) Carcinogenic Effects of Benzene: An Update,
National Center for Environmental Assessment, Washington, DC.
EPA600-P-97-001F. Enter report number at the following search page,
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf//SearchPubs?Openform.
\19\ Leukemia is a blood disease in which the white blood cells
are abnormal in type or number. Leukemia may be divided into
nonlymphocytic (granulocytic) leukemias and lymphocytic leukemias.
Nonlymphocytic leukemia generally involves the types of white blood
cells (leukocytes) that are involved in engulfing, killing, and
digesting bacteria and other parasites (phagocytosis) as well as
releasing chemicals involved in allergic and immune responses. This
type of leukemia may also involve erythroblastic cell types
(immature red blood cells). Lymphocytic leukemia involves the
lymphocyte type of white blood cell that is responsible for antibody
and cell-mediated immune responses. Both nonlymphocytic and
lymphocytic leukemia may, in turn, be separated into acute (rapid
and fatal) and chronic (lingering, lasting) forms. For example in
acute myeloid leukemia there is diminished production of normal red
blood cells (erythrocytes), granulocytes, and platelets (control
clotting), which leads to death by anemia, infection, or hemorrhage.
These events can be rapid. In chronic myeloid leukemia (CML) the
leukemic cells retain the ability to differentiate (i.e., be
responsive to stimulatory factors) and perform function; later there
is a loss of the ability to respond.
\20\ U.S. EPA (1985) Environmental Protection Agency, Interim
quantitative cancer unit risk estimates due to inhalation of
benzene, prepared by the Office of Health and Environmental
Assessment, Carcinogen Assessment Group, Washington, DC for the
Office of Air Quality Planning and Standards, Washington, DC, 1985.
\21\ U.S. EPA (1993) Motor Vehicle-Related Air Toxics Study.
Office of Mobile Sources, Ann Arbor, MI.
http://www.epa.gov/otaq/regs/toxics/tox_archive.htm.
\22\ International Agency for Research on Cancer (IARC) (1982)
IARC monographs on the evaluation of carcinogenic risk of chemicals
to humans, Volume 29, Some industrial chemicals and dyestuffs,
International Agency for Research on Cancer, World Health
Organization, Lyon, France, p. 345-389.
\23\ U.S. EPA (1998) Carcinogenic Effects of Benzene: An Update,
National Center for Environmental Assessment, Washington, DC.
EPA600-P-97-001F. Enter report number at the following search page,
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf//SearchPubs?Openform.
\24\ Irons, R.D., W.S. Stillman, D.B. Colagiovanni, and V.A.
Henry (1992) Synergistic action of the benzene metabolite
hydroquinone on myelopoietic stimulating activity of granulocyte/
macrophage colony-stimulating factor in vitro, Proc. Natl. Acad.
Sci. 89:3691-3695.
\25\ U.S. EPA (1998) Carcinogenic Effects of Benzene: An Update,
National Center for Environmental Assessment, Washington, DC.
EPA600-P-97-001F. Enter report number at the following search page,
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf//SearchPubs?Openform.

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The latest assessment by EPA estimates the excess risk of
developing leukemia from inhalation exposure to benzene at 2.2 x
10-6 to 7.8 x 10-6 per [mu]g/m3. In
other words, there is an estimated risk of about two to eight excess
leukemia cases in one million people exposed to 1 [mu]g/m3
of benzene over a lifetime.\26\ This range of unit risks reflects the
MLEs calculated from different exposure assumptions and dose-response
models that are linear at low doses. At present, the true cancer risk
from exposure to benzene cannot be ascertained, even though dose-
response data are used in the quantitative cancer risk analysis,
because of uncertainties in the low-dose exposure scenarios and lack of
clear understanding of the mode of action. A range of estimates of risk
is recommended, each having equal scientific plausibility. There are
confidence intervals associated with the MLE range that reflect
variation of the observed data used to develop dose-response values.
For the upper end of the MLE range, the 5th and 95th percentile values
are about a factor of 5 lower and higher than the best fit value. The
upper end of the MLE range was used in NATA.
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\26\ U.S. EPA (1998) Carcinogenic Effects of Benzene: An Update,
National Center for Environmental Assessment, Washington, DC.
EPA600-P-97-001F. Enter report number at the following search page,
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf//SearchPubs?Openform.

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It should be noted that not enough information is known to
determine the slope of the dose-response curve at environmental levels
of exposure and to provide a sound scientific basis to choose any
particular extrapolation/exposure model to estimate human cancer risk
at low doses. EPA risk assessment guidelines suggest using an
assumption of linearity of dose response when (1) there is an absence
of sufficient information on modes of action or (2) the mode of action
information indicates that the dose-response curve at low dose is or is
expected to be linear.\27\ Since the mode of action for benzene
carcinogenicity is unknown, the current cancer unit risk estimate
assumes linearity of the low-dose response. Data that were considered
by EPA in its carcinogenic update suggested that the dose-response
relationship at doses below those examined in the studies reviewed in
EPA's most recent benzene assessment may be supralinear. Such a
relationship could support the inference that cancer risks are as high
or are higher than the estimates provided in the existing EPA
assessment.\28\ Data discussed in the EPA IRIS assessment suggest that
genetic abnormalities occur at low exposure in humans, and the
formation of toxic metabolites plateaus above 25 ppm (80,000 [mu]/
m3).\29\ More recent data on benzene adducts in humans,
published after the most recent IRIS assessment, suggest that the
enzymes involved in benzene metabolism start to saturate at exposure
levels as low as 1 ppm.30, 31, 32 These data highlight the
importance of ambient exposure levels and their contribution to
benzene-related adducts. Because there is a transition from linear to
saturable metabolism below 1 ppm, the assumption of low-dose linearity
extrapolated from much higher exposures could lead to substantial
underestimation of leukemia risks. This is consistent with recent
epidemiological data which also suggest a supralinear exposure-response
relationship and which ``[extend] evidence for hematopoietic cancer
risks to levels substantially lower than had previously been
established.'' 33, 34, 35 These data are from the largest
cohort studies done to date with individual worker exposure estimates.
However, these data have not yet been formally evaluated by EPA as part
of the IRIS review process, and it is not clear how they might
influence low-dose risk estimates. A better understanding of the
biological mechanism of benzene-induced leukemia is needed.
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\27\ U.S. EPA (2005) Guidelines for Carcinogen Risk Assessment.
Report No. EPA/630/P-03/001F.
http://cfpub.epa.gov/ncea/raf/recordisplay.cfm?deid=116283.
\28\ U.S. EPA (1998) Carcinogenic Effects of Benzene: An Update.
EPA/600/P-97/001F.
\29\ Rothman, N; Li, GL; Dosemeci, M; et al. (1996)
Hematotoxicity among Chinese workers heavily exposed to benzene. Am.
J. Indust. Med. 29:236-246.
\30\ Rappaport, S.M.; Waidyanatha, S.; Qu, Q.; Shore, R.; Jin,
X.; Cohen, B.; Chen, L.; Melikian, A.; Li, G.; Yin, S.; Yan, H.; Xu,
B.; Mu, R.; Li, Y.; Zhang, X.; and Li, K. (2002) Albumin adducts of
benzene oxide and 1,4-benzoquinone as measures of human benzene
metabolism. Cancer Research 62:1330-1337.
\31\ Rappaport, S.M.; Waidyanatha, S.; Qu, Q.; Yeowell-
O'Connell, K.; Rothman, N.; Smith M.T.; Zhang, L.; Qu, Q.; Shore,
R.; Li, G.; Yin, S. (2005) Protein adducts as biomarkers of human
enzene metabolism. Chem Biol Interact. 153-154:103-109.
\32\ Lin, Y-S., Vermeulen, R., Tsai, C.H., Suramya, W., Lan, Q.,
Rothman, N., Smith, M.T., Zhang, L., Shen, M., Songnian, Y., Kim,
S., Rappaport, S.M. (2006) Albumin adducts of electrophilic benzene
metabolites in benzene-exposed and control workers. Environ Health Perspec.
\33\ Hayes, R.B.; Yin, S.; Dosemeci, M.; Li, G.; Wacholder, S.;
Travis, L.B.; Li, C.; Rothman, N.; Hoover, R.N.; and Linet, M.S.
(1997) Benzene and the dose-related incidence of hematologic
neoplasms in China. J. Nat. Cancer Inst. 89:1065-1071.
\34\ Hayes, R.B.; Songnian, Y.; Dosemeci, M.; and Linet, M.
(2001) Benzene and lymphohematopoietic malignancies in humans. Am.
J. Indust. Med. 40:117-126.
\35\ Lan, Q.; Zhang, L., Li, G., Vermeulen, R., et al. (2004).
Hematotoxicity in Workers Exposed to Low Levels of Benzene. Science
306: 1774-1776.
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Children may represent a subpopulation at increased risk from
benzene exposure, due to factors that could increase their
susceptibility. Children may have a higher unit body weight exposure
because of their heightened activity patterns which can increase their
exposures, as well as different ventilation tidal volumes and
frequencies, factors that influence uptake. This could entail a greater
lifetime risk of leukemia and other toxic effects from exposures
occurring during childhood, if children are exposed to benzene at
similar levels as adults. There is limited information from two studies
regarding an increased risk to children whose parents have been
occupationally exposed to benzene.36, 37 Data from animal
studies have shown benzene exposures result in damage to the
hematopoietic (blood cell formation) system during
development.38, 39, 40

[[Page 8437]]

Also, key changes related to the development of childhood leukemia
occur in the developing fetus.\41\ Several studies have reported that
genetic changes related to eventual leukemia development occur before
birth. For example, there is one study of genetic changes in twins who
developed T cell leukemia at 9 years of age.\42\ An association between
traffic volume, residential proximity to busy roads and occurrence of
childhood leukemia has also been identified in some studies, although
some studies show no association.
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\36\ Shu, X.O.; Gao, Y.T.; Brinton, L.A.; et al. (1988) A
population-based case-control study of childhood leukemia in
Shanghai. Cancer 62:635-644.
\37\ McKinney P.A.; Alexander, F.E.; Cartwright, R.A.; et al.
(1991) Parental occupations of children with leukemia in west
Cumbria, north Humberside, and Gateshead, Br. Med. J. 302:681-686.
\38\ Keller, KA; Snyder, CA. (1986) Mice exposed in utero to low
concentrations of benzene exhibit enduring changes in their colony
forming hematopoietic cells. Toxicology 42:171-181.
\39\ Keller, KA; Snyder, CA. (1988) Mice exposed in utero to 20
ppm benzene exhibit altered numbers of recognizable hematopoietic
cells up to seven weeks after exposure. Fundam. Appl. Toxicol.
10:224-232.
\40\ Corti, M; Snyder, CA. (1996) Influences of gender,
development, pregnancy and ethanol consumption on the hematotoxicity
of inhaled 10 ppm benzene. Arch. Toxicol. 70:209-217.
\41\ U.S. EPA. (2002). Toxicological Review of Benzene
(Noncancer Effects). National Center for Environmental Assessment,
Washington, DC. Report No. EPA/635/R-02/001F.
http://www.epa.gov/iris/toxreviews/0276-tr.pdf.
\42\ Ford, AM; Pombo-de-Oliveira, MS; McCarthy, KP; MacLean, JM;
Carrico, KC; Vincent, RF; Greaves, M. (1997) Monoclonal origin of
concordant T-cell malignancy in identical twins. Blood 89:281-285.
---------------------------------------------------------------------------

A number of adverse noncancer health effects, including blood
disorders such as preleukemia and aplastic anemia, have also been
associated with long-term exposure to benzene.43, 44 People
with long-term occupational exposure to benzene have experienced
harmful effects on the blood-forming tissues, especially in the bone
marrow. These effects can disrupt normal blood production and suppress
the production of important blood components, such as red and white
blood cells and blood platelets, leading to anemia (a reduction in the
number of red blood cells), leukopenia (a reduction in the number of
white blood cells), or thrombocytopenia (a reduction in the number of
blood platelets, thus reducing the ability of blood to clot). Chronic
inhalation exposure to benzene in humans and animals results in
pancytopenia,\45\ a condition characterized by decreased numbers of
circulating erythrocytes (red blood cells), leukocytes (white blood
cells), and thrombocytes (blood platelets).46, 47
Individuals that develop pancytopenia and have continued exposure to
benzene may develop aplastic anemia, whereas others exhibit both
pancytopenia and bone marrow hyperplasia (excessive cell formation), a
condition that may indicate a preleukemic state.48, 49 The
most sensitive noncancer effect observed in humans, based on current
data, is the depression of the absolute lymphocyte count in
blood.50, 51
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\43\ Aksoy, M. (1989) Hematotoxicity and carcinogenicity of
benzene. Environ. Health Perspect. 82:193-197.
\44\ Goldstein, B.D. (1988) Benzene toxicity. Occupational
medicine. State of the Art Reviews 3: 541-554.
\45\ Pancytopenia is the reduction in the number of all three
major types of blood cells (erythrocytes, or red blood cells,
thrombocytes, or platelets, and leukocytes, or white blood cells).
In adults, all three major types of blood cells are produced in the
bone marrow of the skeletal system. The bone marrow contains
immature cells, known as multipotent myeloid stem cells, that later
differentiate into the various mature blood cells. Pancytopenia
results from a reduction in the ability of the red bone marrow to
produce adequate numbers of these mature blood cells.
\46\ Aksoy, M. (1991) Hematotoxicity, leukemogenicity and
carcinogenicity of chronic exposure to benzene. In: Arinc, E.;
Schenkman, J.B.; Hodgson, E., Eds. Molecular Aspects of
Monooxygenases and Bioactivation of Toxic Compounds. New York:
Plenum Press, pp. 415-434.
\47\ Goldstein, B.D. (1988) Benzene toxicity. Occupational
medicine. State of the Art Reviews 3: 541-554.
\48\ Aksoy, M., S. Erdem, and G. Dincol. (1974) Leukemia in
shoe-workers exposed chronically to benzene. Blood 44:837.
\49\ Aksoy, M. and K. Erdem. (1978) A follow-up study on the
mortality and the development of leukemia in 44 pancytopenic
patients associated with long-term exposure to benzene. Blood 52: 285-292.
\50\ Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E.
Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu, M.T. Smith, N. Titenko-
Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B. Hayes (1996)
Hematotoxicity among Chinese workers heavily exposed to benzene. Am.
J. Ind. Med. 29: 236-246.
\51\ EPA 2005 ``Full IRIS Summary for Benzene (CASRN 71-43-2)''
Environmental Protection Agency, Integrated Risk Information System
(IRIS), Office of Health and Environmental Assessment, Environmental
Criteria and Assessment Office, Cincinnati, OH,
http://www.epa.gov/iris/subst/0276.htm.

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EPA's inhalation reference concentration (RfC) for benzene is 30
[mu]g/m3, based on suppressed absolute lymphocyte counts as
seen in humans under occupational exposure conditions. The overall
confidence in this RfC is medium. Since development of this RfC, human
reports of benzene's hematotoxic effects have been published in the
literature that provides data suggesting a wide range of hematological
endpoints that are affected at occupational exposures of less than 5
ppm (about 16 mg/m3)\52\ and at air levels of 1 ppm (about 3
mg/m3) or less among genetically susceptible
populations.\53\ One recent study found benzene metabolites in mouse
liver and bone marrow at environmental doses, indicating that even
concentrations in urban air can elicit a biochemical response in
rodents that indicates toxicity.\54\ EPA has not formally evaluated
these recent studies as part of the IRIS review process to determine
whether or not they will lead to a change in the current RfC. EPA does
not currently have an acute reference concentration for benzene. The
Agency for Toxic Substances and Disease Registry Minimal Risk Level for
acute exposure to benzene is 160 [mu]g/m3 for 1-14 days exposure.
---------------------------------------------------------------------------

\52\ Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et
al. (2002). Hematological changes among Chinese workers with a broad
range of benzene exposures. Am. J. Industr. Med. 42: 275-285.
\53\ Lan, Q.; Zhang, L., Li, G., Vermeulen, R., et al. (2004).
Hematotoxicity in Workers Exposed to Low Levels of Benzene. Science
306: 1774-1776.
\54\ Turtletaub, K.W. and Mani, C. (2003). Benzene metabolism in
rodents at doses relevant to human exposure from Urban Air. Res Rep
Health Effect Inst 113.
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ii. 1,3-Butadiene
EPA has characterized 1,3-butadiene, a hydrocarbon, as a
leukemogen, carcinogenic to humans by inhalation.55 56 The
specific mechanisms of 1,3-butadiene-induced carcinogenesis are
unknown; however, it is virtually certain that the carcinogenic effects
are mediated by genotoxic metabolites of 1,3-butadiene. Animal data
suggest that females may be more sensitive than males for cancer
effects; nevertheless, there are insufficient data in humans from which
to draw any conclusions on potentially sensitive subpopulations. The
upper bound cancer unit risk estimate is 0.08 per ppm or 3 x 10
-5 per [mu]g/m3 (based primarily on linear
modeling and extrapolation of human data). In other words, it is
estimated that approximately 30 persons in one million exposed to 1
[mu]g/m3 of 1,3-butadiene continuously for their lifetime
would develop cancer as a result of this exposure. The human
incremental lifetime unit cancer risk estimate is based on
extrapolation from leukemias observed in an occupational epidemiologic
study.57 58 This estimate includes a two-fold adjustment to
the epidemiologic-based unit cancer risk applied to reflect evidence
from the rodent bioassays suggesting that the epidemiologic-based
estimate (from males) may underestimate total cancer

[[Page 8438]]

risk from 1,3-butadiene exposure in the general population,
particularly for breast cancer in females. A recent study extended the
investigation of 1,3-butadiene exposure and leukemia among synthetic
rubber industry workers.\59\ The results of this study strengthen the
evidence for the relationship between 1,3-butadiene exposure and
lymphohematopoietic cancer. This relationship was found to persist
after controlling for exposure to other toxics in this work environment.
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\55\ U.S. EPA. (2002). Health Assessment of 1,3-Butadiene.
Office of Research and Development, National Center for
Environmental Assessment, Washington Office, Washington, DC. Report
No. EPA600-P-98-001F.
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54499.
\56\ EPA 2005 ``Full IRIS Summary for 1,3-butadiene (CASRN 106-
99-0)'' Environmental Protection Agency, Integrated Risk Information
System (IRIS), Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH,
http://www.epa.gov/iris/subst/0139.htm.
\57\ Delzell, E, N. Sathiakumar, M. Macaluso, et al. (1995). A
follow-up study of synthetic rubber workers. Submitted to the
International Institute of Synthetic Rubber Producers. University of
Alabama at Birmingham. October 2, 1995.
\58\ EPA 2005 ``Full IRIS Summary for 1,3-butadiene (CASRN 106-
99-0)'' Environmental Protection Agency, Integrated Risk Information
System (IRIS), Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH,
http://www.epa.gov/iris/subst/0139.htm.
\59\ Delzell, E., Sathiakumar, N., Graff, J., Macaluso, M.,
Maldonado, G., Matthews, R. (2006) An updated study of mortality
among North American synthetic rubber industry workers. Health
Effects Institute Report Number 132.
---------------------------------------------------------------------------

1,3-Butadiene also causes a variety of reproductive and
developmental effects in mice; no human data on these effects are
available. The most sensitive effect was ovarian atrophy observed in a
lifetime bioassay of female mice.\60\ Based on this critical effect and
the benchmark concentration methodology, an RfC was calculated. This
RfC for chronic health effects is 0.9 ppb, or about 2 [mu]g/
m3. Confidence in the inhalation RfC is medium.
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\60\ Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996)
Subchronic toxicity of 4-vinylcyclohexene in rats and mice by
inhalation. Fundam. Appl. Toxicol. 32:1-10.
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iii. Formaldehyde
Since 1987, EPA has classified formaldehyde, a hydrocarbon, as a
probable human carcinogen based on evidence in humans and in rats,
mice, hamsters, and monkeys.\61\ EPA's current IRIS summary provides an
upper bound cancer unit risk estimate of 1.3 x 10-5 per
[mu]g/m3.\62\ In other words, there is an estimated risk of
about thirteen excess leukemia cases in one million people exposed to 1
[mu]g/m3 of formaldehyde over a lifetime.
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\61\ U.S. EPA (1987). Assessment of Health Risks to Garment
Workers and Certain Home Residents From Exposure to Formaldehyde,
Office of Pesticides and Toxic Substances, April 1987.
\62\ U.S. EPA (1989). Integrated Risk Information System File
for Formaldehyde. This material is available electronically at
http://www.epa.gov/iris/subst/0419.htm.

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EPA is currently reviewing recently published epidemiological data.
For instance, research conducted by the National Cancer Institute (NCI)
found an increased risk of nasopharyngeal cancer and
lymphohematopoietic malignancies such as leukemia among workers exposed
to formaldehyde.63 64 NCI is currently performing an update
of these studies. A recent National Institute of Occupational Safety
and Health (NIOSH) study of garment workers also found increased risk
of death due to leukemia among workers exposed to formaldehyde.\65\
Extended follow-up of a cohort of British chemical workers did not find
evidence of an increase in nasopharyngeal or lymphohematopoeitic
cancers, but a continuing statistically significant excess in lung
cancers was reported.\66\
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\63\ Hauptmann, M.; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.;
Blair, A. 2003. Mortality from lymphohematopoietic malignancies
among workers in formaldehyde industries. Journal of the National
Cancer Institute 95: 1615-1623.
\64\ Hauptmann, M..; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.;
Blair, A. 2004. Mortality from solid cancers among workers in
formaldehyde industries. American Journal of Epidemiology 159: 1117-1130.
\65\ Pinkerton, L. E. 2004. Mortality among a cohort of garment
workers exposed to formaldehyde: an update. Occup. Environ. Med. 61:
193-200.
\66\ Coggon, D, EC Harris, J Poole, KT Palmer. 2003. Extended
follow-up of a cohort of British chemical workers exposed to
formaldehyde. J National Cancer Inst. 95:1608-1615.
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Based on the developments of the last decade, in 2004, the working
group of the International Agency for Research on Cancer concluded that
formaldehyde is carcinogenic to humans (Group 1 classification) on the
basis of sufficient evidence in humans and sufficient evidence in
experimental animals--a higher classification than previous IARC
evaluations. In addition, the National Institute of Environmental
Health Sciences recently nominated formaldehyde for reconsideration as
a known human carcinogen under the National Toxicology Program. Since
1981 it has been listed as a ``reasonably anticipated human
carcinogen.'' Recently the German Federal Institute for Risk Assessment
determined that formaldehyde is a known human carcinogen.\67\
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\67\ Bundesinstitut fur Risikobewertung (BfR) Toxicological
Assessment of Formaldehyde. Opinion of BfR No. 023/2006 of 30 March 2006.
http://www.bfr.bund.de/cm/290/toxicological_assessment_of_formaldehyde.pdf.

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In the past 15 years there has been substantial research on the
inhalation dosimetry for formaldehyde in rodents and primates by the
CIIT Centers for Health Research, with a focus on use of rodent data
for refinement of the quantitative cancer dose-response
assessment.68 69 70 CIIT's risk assessment of formaldehyde
incorporated mechanistic and dosimetric information on formaldehyde.
The risk assessment analyzed carcinogenic risk from inhaled
formaldehyde using approaches that were consistent with EPA's draft
guidelines for carcinogenic risk assessment. In 2001, Environment
Canada relied on this cancer dose-response assessment in their
assessment of formaldehyde.\71\ In 2004, EPA also relied on this cancer
unit risk estimate during the development of the plywood and composite
wood products national emissions standards for hazardous air pollutants
(NESHAPs).\72\ In these rules, EPA concluded that the CIIT work
represented the best available application of the available mechanistic
and dosimetric science on the dose-response for portal of entry cancers
due to formaldehyde exposures. EPA is reviewing the recent work cited
above from the NCI and NIOSH, as well as the analysis by the CIIT
Centers for Health Research and other studies, as part of a reassessment
of the human hazard and dose-response associated with formaldehyde.
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\68\ Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D
Kalisak, J Preston, and FJ Miller. 2003. Biologically motivated
computational modeling of formaldehyde carcinogenicity in the F344
rat. Tox. Sci. 75: 432-447.
\69\ Conolly, RB, JS Kimbell, D Janszen, PM Schlosser, D
Kalisak, J Preston, and FJ Miller. 2004. Human respiratory tract
cancer risks of inhaled formaldehyde: Dose-response predictions
derived from biologically-motivated computational modeling of a
combined rodent and human dataset. Tox. Sci. 82: 279-296.
\70\ Chemical Industry Institute of Toxicology (CIIT). 1999.
Formaldehyde: Hazard characterization and dose-response assessment
for carcinogenicity by the route of inhalation. CIIT, September 28,
1999. Research Triangle Park, NC.
\71\ Health Canada. 2001. Priority Substances List Assessment
Report. Formaldehyde. Environment Canada, Health Canada, February 2001.
\72\ U.S. EPA. 2004. National Emission Standards for Hazardous
Air Pollutants for Plywood and Composite Wood Products Manufacture:
Final Rule. (69 FR 45943, 7/30/04).
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Noncancer effects of formaldehyde have been observed in humans and
several animal species and include irritation to eye, nose and throat
tissues in conjunction with increased mucous secretions.
iv. Acetaldehyde
Acetaldehyde, a hydrocarbon, is classified in EPA's IRIS database
as a probable human carcinogen and is considered toxic by
inhalation.\73\ Based on nasal tumors in rodents, the upper confidence
limit estimate of a lifetime extra cancer risk from continuous
acetaldehyde exposure is about 2.2 x 10-6 per [mu]g/
m3. In other words, it is estimated that about 2 persons in
one million exposed to 1 [mu]g/m3 acetaldehyde continuously
for their lifetime (70 years) would develop cancer as a result of their
exposure, although the risk could be as low as zero. In short-term (4
week) rat studies, compound-related histopathological changes were
observed only in the respiratory system at various concentration levels
of exposure.74 75

[[Page 8439]]

Data from these studies showing degeneration of the olfactory
epithelium were found to be sufficient for EPA to develop an RfC for
acetaldehyde of 9 [mu]g/m3. Confidence in the principal
study is medium and confidence in the database is low, due to the lack
of chronic data establishing a no observed adverse effect level and due
to the lack of reproductive and developmental toxicity data. Therefore,
there is low confidence in the RfC. The agency is currently conducting
a reassessment of risk from inhalation exposure to acetaldehyde.
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\73\ U.S. EPA. 1988. Integrated Risk Information System File of
Acetaldehyde. This material is available electronically at
http://www.epa.gov/iris/subst/0290.htm.
\74\ Appleman, L. M., R. A. Woutersen, V. J. Feron, R. N.
Hooftman, and W. R. F. Notten. (1986). Effects of the variable
versus fixed exposure levels on the toxicity of acetaldehyde in
rats. J. Appl. Toxicol. 6: 331-336.
\75\ Appleman, L.M., R.A. Woutersen, and V.J. Feron. (1982).
Inhalation toxicity of acetaldehyde in rats. I. Acute and subacute
studies. Toxicology. 23: 293-297.
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The primary acute effect of exposure to acetaldehyde vapors is
irritation of the eyes, skin, and respiratory tract.\76\ Some
asthmatics have been shown to be a sensitive subpopulation to
decrements in functional expiratory volume (FEV1 test) and
bronchoconstriction upon acetaldehyde inhalation.\77\
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\76\ U.S. EPA (1988). Integrated Risk Information System File of
Acetaldehyde. This material is available electronically at
http://www.epa.gov/iris/subst/0290.htm.
\77\ Myou, S.; Fujimura, M.; Nishi K.; Ohka, T.; and Matsuda, T.
(1993) Aerosolized acetaldehyde induces histamine-mediated
bronchoconstriction in asthmatics. Am. Rev. Respir. Dis.148(4 Pt 1): 940-3.
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v. Acrolein
Acrolein, a hydrocarbon, is intensely irritating to humans when
inhaled, with acute exposure resulting in upper respiratory tract
irritation and congestion. The Agency has developed an RfC for acrolein
of 0.02 [mu]g/m3.\78\ The overall confidence in the RfC
assessment is judged to be medium. The Agency is also currently in the
process of conducting an assessment of acute health effects for
acrolein. EPA determined in 2003 using the 1999 draft cancer guidelines
that the human carcinogenic potential of acrolein could not be
determined because the available data were inadequate. No information
was available on the carcinogenic effects of acrolein in humans and the
animal data provided inadequate evidence of carcinogenicity.
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\78\ U.S. Environmental Protection Agency (2003) Integrated Risk
Information System (IRIS) on Acrolein. National Center for
Environmental Assessment, Office of Research and Development,
Washington, D.C. 2003. This material is available electronically at
http://www.epa.gov/iris/subst/0364.htm.

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vi. Polycyclic Organic Matter (POM)
POM is generally defined as a large class of organic compounds
which have multiple benzene rings and a boiling point greater than 100
degrees Celsius. Many of the compounds included in the class of
compounds known as POM are classified by EPA as probable human
carcinogens based on animal data. One of these compounds, naphthalene,
is discussed separately below.
Polycyclic aromatic hydrocarbons (PAHs) are a chemical subset of
POM. In particular, EPA frequently obtains data on 16 of these POM
compounds. Recent studies have found that maternal exposures to PAHs in
a population of pregnant women were associated with several adverse
birth outcomes, including low birth weight and reduced length at birth,
as well as impaired cognitive development at age
three.79, 80 These studies are discussed in the Regulatory
Impact Analysis.
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\79\ Perera, F.P.; Rauh, V.; Tsai, W-Y.; et al. (2002) Effect of
transplacental exposure to environmental pollutants on birth
outcomes in a multiethnic population. Environ Health Perspect. 111:
201-205.
\80\ Perera, F.P.; Rauh, V.; Whyatt, R.M.; Tsai, W.Y.; Tang, D.;
Diaz, D.; Hoepner, L.; Barr, D.; Tu, Y.H.; Camann, D.; Kinney, P.
(2006) Effect of prenatal exposure to airborne polycyclic aromatic
hydrocarbons on neurodevelopment in the first 3 years of life among
inner-city children. Environ Health Perspect 114: 1287-1292.
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vii. Naphthalene
Naphthalene is a PAH compound consisting of two benzene rings fused
together with two adjacent carbon atoms common to both rings. In 2004,
EPA released an external review draft of a reassessment of the
inhalation carcinogenicity of naphthalene.\81\ The draft reassessment,
External Review Draft, IRIS Reassessment of the Inhalation
Carcinogenicity of Naphthalene, U.S. EPA, completed external peer
review in 2004 by Oak Ridge Institute for Science and Education.\82\
Based on external comments, additional analyses are being considered.
California EPA has released a new risk assessment for naphthalene with
a cancer unit risk estimate of 3x10 -5 per [mu]g/
m3.\83\ The California EPA value was used in the 1999 NATA
and in the analyses done for this rule. In addition, IARC has
reevaluated naphthalene and re-classified it as Group 2B: possibly
carcinogenic to humans.\84\ Current risk estimates for naphthalene are
based on extrapolations from rodent studies conducted at higher doses.
At present, human data are inadequate for developing estimates.
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\81\ U.S. EPA (1998) Integrated Risk Information System (IRIS)
summary on Naphthalene. National Center for Environmental
Assessment, Office of Research and Development, Washington, D.C.
2003. This material is available electronically at
http://www.epa.gov/iris/subst/0436.htm.
\82\ Oak Ridge Institute for Science and Education. (2004)
External Peer Review for the IRIS Reassessment of the Inhalation
Carcinogenicity of Naphthalene. August 2004.
http://cfpub2.epa.gov/ncea/cfm/recordisplay.cfm?deid=86019.
\83\ California EPA. (2004) Long Term Health Effects of Exposure
to Naphthalene. Office of Environmental Health Hazard Assessment.
http://www.oehha.ca.gov/air/toxic_contaminants/draftnaphth.html.
\84\ International Agency for Research on Cancer (IARC). (2002)
Monographs on the Evaluation of the Carcinogenic Risk of Chemicals
for Humans. Vol. 82. Lyon, France.
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The current EPA IRIS assessment includes noncancer data on
hyperplasia and metaplasia in nasal tissue that form the basis of an
inhalation RfC of 3 [mu]g/m3.\85\ The principal study was
given medium confidence because adequate numbers of animals were used,
and the severity of nasal effects increased at the higher exposure
concentration. However, the study produced high mortality and
hematological evaluation was not conducted beyond 14 days. The database
was given a low-to-medium confidence rating because there are no
chronic or subchronic inhalation studies in other animal species, and
there are no reproductive or developmental studies for inhalation
exposure. In the absence of human or primate toxicity data, the
assumption is made that nasal responses in mice to inhaled naphthalene
are relevant to humans; however, it cannot be said with certainty that
this RfC for naphthalene based on nasal effects will be protective for
hemolytic anemia and cataracts, the more well-known human effects from
naphthalene exposure. As a result, we have medium confidence in the RfC.
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\85\ EPA 2005 ``Full IRIS Summary for Naphthalene (CASRN 91-20-
3)'' Environmental Protection Agency, Integrated Risk Information
System (IRIS), Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH
http://www.epa.gov/iris/subst/0436.htm.

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viii. Diesel Exhaust
In EPA's Diesel Health Assessment Document (HAD),\86\ diesel
exhaust was classified as likely to be carcinogenic to humans by
inhalation at environmental exposures, in accordance with the revised
draft 1996/1999 EPA cancer guidelines. A number of other agencies
(National Institute for Occupational Safety and Health, the
International Agency for Research on Cancer, the World Health
Organization, California EPA, and the U.S. Department of Health and
Human Services) have made similar classifications. EPA concluded in the
Diesel HAD that it is not possible currently to calculate a cancer unit
risk for diesel exhaust due to a variety of factors that limit the
current studies,

[[Page 8440]]

such as limited quantitative exposure histories in occupational groups
investigated for lung cancer.
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\86\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/600/8-90/057F Office of Research and
Development, Washington, DC. This document is available
electronically at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060.

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However, in the absence of a cancer unit risk, the EPA Diesel HAD
sought to provide additional insight into the significance of the
cancer hazard by estimating possible ranges of risk that might be
present in the population. An exploratory analysis was used to
characterize a possible risk range by comparing a typical environmental
exposure level for highway diesel sources to a selected range of
occupational exposure levels. The occupationally observed risks were
then proportionally scaled according to the exposure ratios to obtain
an estimate of the possible environmental risk. A number of
calculations are needed to accomplish this, and these can be seen in
the EPA Diesel HAD. The outcome was that environmental risks from
diesel exhaust exposure could range from a low of 10-4 to
10-5 to as high as 10-3, reflecting the range of
occupational exposures that could be associated with the relative and
absolute risk levels observed in the occupational studies. Because of
uncertainties, the analysis acknowledged that the risks could be lower
than 10-4 or 10-5, and a zero risk from diesel
exhaust exposure was not ruled out.
Noncancer health effects of acute and chronic exposure to diesel
exhaust emissions are also of concern to the Agency. EPA derived an RfC
from consideration of four well-conducted chronic rat inhalation
studies showing adverse pulmonary effects.87 88 89 90 The
RfC is 5 [mu]g/m3 for diesel exhaust as measured by diesel
PM. This RfC does not consider allergenic effects such as those
associated with asthma or immunologic effects. There is growing
evidence, discussed in the Diesel HAD, that diesel exhaust can
exacerbate these effects, but the exposure-response data are presently
lacking to derive an RfC. The EPA Diesel HAD states, ``With DPM [diesel
particulate matter] being a ubiquitous component of ambient PM, there
is an uncertainty about the adequacy of the existing DE [diesel
exhaust] noncancer database to identify all of the pertinent DE-caused
noncancer health hazards'' (p. 9-19).
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\87\ Ishinishi, N; Kuwabara, N; Takaki, Y; et al. (1988) Long-
term inhalation experiments on diesel exhaust. In: Diesel exhaust
and health risks. Results of the HERP studies. Ibaraki, Japan:
Research Committee for HERP Studies; pp. 11-84.
\88\ Heinrich, U; Fuhst, R; Rittinghausen, S; et al. (1995)
Chronic inhalation exposure of Wistar rats and two different strains
of mice to diesel engine exhaust, carbon black, and titanium
dioxide. Inhal. Toxicol. 7:553-556.
\89\ Mauderly, JL; Jones, RK; Griffith, WC; et al. (1987) Diesel
exhaust is a pulmonary carcinogen in rats exposed chronically by
inhalation. Fundam. Appl. Toxicol. 9:208-221.
\90\ Nikula, KJ; Snipes, MB; Barr, EB; et al. (1995) Comparative
pulmonary toxicities and carcinogenicities of chronically inhaled
diesel exhaust and carbon black in F344 rats. Fundam. Appl. Toxicol.
25:80-94.
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The Diesel HAD also briefly summarizes health effects associated
with ambient PM and discusses the EPA's annual National Ambient Air
Quality Standard (NAAQS) of 15 [mu]g/m3. There is a much
more extensive body of human data showing a wide spectrum of adverse
health effects associated with exposure to ambient PM, of which diesel
exhaust is an important component. The PM_2.5 NAAQS is
designed to provide protection from the noncancer and premature
mortality effects of PM_2.5 as a whole, of which diesel PM is
a constituent.
c. Gasoline PM
Beyond the specific areas of quantifiable risk discussed above in
section III.C, EPA is also currently investigating gasoline PM.
Gasoline exhaust is a complex mixture that has not been evaluated in
EPA's IRIS. Gasoline exhaust is a ubiquitous source of particulate
matter, contributing to the health effects observed for ambient PM
which is discussed extensively in the EPA Particulate Matter Criteria
Document.\91\ The PM Criteria Document notes that the PM components of
gasoline and diesel engine exhaust are hypothesized, important
contributors to the observed increases in lung cancer incidence and
mortality associated with ambient PM_2.5.\92\ Gasoline PM is
also a component of near-roadway emissions that may be contributing to
the health effects observed in people who live near roadways (see
section III.F). There is also emerging evidence for the mutagenicity
and cytotoxicity of gasoline exhaust and gasoline PM. Seagrave et al.
investigated the combined particulate and semivolatile organic
fractions of gasoline engine emissions in various animal and bioassay
tests.\93\ The authors suggest that emissions from gasoline engines are
mutagenic and can induce inflammation and have cytotoxic effects.
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\91\ U.S. EPA (2004) Air Quality Criteria for Particulate
Matter: Volume 1. Research Triangle Park, NC: National Center for
Environmental Assessment--RTP Office; Report No. EPA/600/P-99/002aF.
Enter report number at the following search page,
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf//SearchPubs?Openform.
\92\ U.S. EPA (2004) Air Quality Criteria for Particulate
Matter: Volume 1. Research Triangle Park, NC: National Center for
Environmental Assessment--RTP Office; Report No. EPA/600/P-99/002aF,
p. 8-318. Enter report number at the following search page,
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf//SearchPubs?Openform.
\93\ Seagrave, J.; McDonald, J.D.; Gigliotti, A.P.; Nikula,
K.J.; Seilkop, S.K.; Gurevich, M. and Mauderly, J.L. (2002)
Mutagenicity and in Vivo Toxicity of Combined Particulate and
Semivolatile Organic Fractions of Gasoline and Diesel Engine
Emissions. Toxicological Sciences 70:212-226.
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EPA is working to improve the understanding of PM emissions from
gasoline engines, including the potential range of emissions and
factors that influence emissions. EPA led a cooperative test program
that recently completed testing approximately 500 randomly procured
vehicles in the Kansas City metropolitan area. The purpose of this
study was to determine the distribution of gasoline PM emissions from
the in-use light-duty fleet. Results from this study are expected to be
available shortly. Preliminary results from this work show the
influence of high emitters on overall gasoline PM emissions and, also,
that gasoline PM emissions increase at lower ambient temperatures in
the in-use fleet. Some source apportionment studies show gasoline and
diesel PM can result in larger contributions to ambient PM than
predicted by EPA emission inventories.\94\ \95\ These source
apportionment studies were one impetus behind conducting the Kansas
City study.
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\94\ Fujita, E.; Watson, M.J.; Chow, M.C.; et al. (1998)
Northern Front Range Air Quality Study, Volume C: Source
apportionment and simulation methods and evaluation. Prepared for
Colorado State University, Cooperative Institute for Research in the
Atmosphere, by Desert Research Institute, Reno, NV.
\95\ Schauer, J.J.; Rogge, W.F.; Hildemann, L.M.; et al. (1996)
Source apportionment of airborne particulate matter using organic
compounds as tracers. Atmos. Environ. 30(22):3837-3855.
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Another issue related to gasoline PM is the effect of gasoline
vehicles and engines on ambient PM, especially secondary PM. Ambient PM
is composed of primary PM emitted directly into the atmosphere and
secondary PM that is formed from chemical reactions in the atmosphere.
The issue of secondary organic aerosol formation from aromatic
precursors such as toluene is an important one to which EPA and others
are paying significant attention. This is discussed in more detail in
section 1.4.1 of the RIA.
d. Near-Roadway Health Effects
Another approach to investigating the collective health effects of
mobile source contaminants is to examine associations between living
near major roads and different adverse health endpoints. These studies
generally examine people living near heavily-trafficked roadways,
typically within several hundred meters, where fresh

[[Page 8441]]

emissions from motor vehicles are not yet fully diluted with background
air.
Several studies have measured elevated concentrations of pollutants
emitted directly by motor vehicles near roadways as compared to overall
urban background levels. These elevated concentrations generally occur
within approximately 200 meters of the road, although the distance may
vary depending on traffic and environmental conditions. Pollutants
measured with elevated concentrations include benzene, polycyclic
aromatic hydrocarbons, carbon monoxide, nitrogen dioxide, black carbon,
and coarse, fine, and ultrafine particulate matter. In addition,
concentrations of road dust, and wear particles from tire and brake use
also show concentration increases in proximity of major roadways.
The near-roadway health studies provide stronger evidence for some
health endpoints than others. Evidence of adverse responses to traffic-
related pollution is strongest for non-allergic respiratory symptoms,
cardiovascular effects, premature adult mortality, and adverse birth
outcomes, including low birth weight and size. Some evidence for new
onset asthma is available, but not all studies have significant
correlations. Lastly, among studies of childhood cancer, in particular
childhood leukemia, evidence is inconsistent. Several small studies
report positive associations, though such effects have not been
observed in two larger studies. As described above, benzene and 1,3-
butadiene are both known human leukemogens in adults. As previously
mentioned, there is evidence of increased risk of leukemia among
children whose parents have been occupationally exposed to benzene.
Though the near-roadway studies are equivocal, taken together with the
laboratory studies and other exposure environments, the data suggest a
potentially serious children's health concern could exist. Additional
research is needed to determine the significance of this potential concern.
Significant scientific uncertainties remain in our understanding of
the relationship between adverse health effects and near-road exposure,
including the exposures of greatest concern, the importance of chronic
versus acute exposures, the role of fuel type (e.g. diesel or gasoline)
and composition (e.g., % aromatics), relevant traffic patterns, the
role of co-stressors including noise and socioeconomic status, and the
role of differential susceptibility within the ``exposed'' populations.
For a more detailed discussion, see Chapter 3 of the Regulatory Impact
Analysis.
These studies provide qualitative evidence that reducing emissions
from on-road mobile sources will provide public health benefits beyond
those that can be quantified using currently available information.

C. Ozone

Many MSATs are part of a larger category of mobile source emissions
known as volatile organic compounds (VOCs), which contribute to the
formation of ozone. Mobile sources contribute significantly to national
emissions of VOCs. In addition, PFCs are a source of VOCs. The vehicle
and PFC standards in this final rule will help reduce emissions of VOCs.
1. Background
Ground-level ozone pollution is formed by the reaction of VOCs and
nitrogen oxides (NO_X) in the lower atmosphere in the
presence of heat and sunlight. These pollutants, often referred to as
ozone precursors, are emitted by many types of pollution sources, such
as highway and nonroad motor vehicles and engines, power plants,
chemical plants, refineries, makers of consumer and commercial
products, industrial facilities, and smaller area sources. The PFC
controls being finalized in this action will help reduce VOC emissions
by reducing evaporation, permeation and spillage from PFCs. The vehicle
controls being finalized will also reduce VOC emissions; however,
because these reductions will occur at cold temperatures the ozone
benefits will be limited.
The science of ozone formation, transport, and accumulation is
complex.\96\ Ground-level ozone is produced and destroyed in a cyclical
set of chemical reactions, many of which are sensitive to temperature
and sunlight. When ambient temperatures and sunlight levels remain high
for several days and the air is relatively stagnant, ozone and its
precursors can build up and result in more ozone than typically would
occur on a single high-temperature day. Ozone also can be transported
into an area from pollution sources found hundreds of miles upwind,
resulting in elevated ozone levels even in areas with low VOC or
NO_X emissions.
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\96\ U.S. EPA, Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document
is available in Docket EPA-HQ-OAR-2005-0036.
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The current ozone National Ambient Air Quality Standards (NAAQS)
established by EPA in 1997 has an 8-hour averaging time.\97\ The 8-hour
ozone NAAQS is based on well-documented science demonstrating that more
people were experiencing adverse health effects at lower levels of
exertion, over longer periods, and at lower ozone concentrations than
addressed by the previous one-hour ozone NAAQS. The current ozone NAAQS
addresses ozone exposures of concern for the general population and
populations most at risk, including children active outdoors, outdoor
workers, and individuals with pre-existing respiratory disease, such as
asthma. The 8-hour ozone NAAQS is met at an ambient air quality
monitoring site when the average of the annual fourth-highest daily
maximum 8-hour average ozone concentration over three years is less
than or equal to 0.084 ppm.
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\97\ EPA's review of the ozone NAAQS is underway and a proposal
is scheduled for June 2007 with a final rule scheduled for March 2008.
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2. Health Effects of Ozone
The health and welfare effects of ozone are well documented and are
assessed in the EPA's 2006 ozone Air Quality Criteria Document (ozone
AQCD) and EPA staff papers.98 99 Ozone can irritate the
respiratory system, causing coughing, throat irritation, and/or
uncomfortable sensation in the chest. Ozone can reduce lung function
and make it more difficult to breathe deeply, and breathing may become
more rapid and shallow than normal, thereby limiting a person's
activity. Ozone can also aggravate asthma, leading to more asthma
attacks that require a doctor's attention and/or the use of additional
medication. Animal toxicologic evidence indicates that with repeated
exposure, ozone can inflame and damage the lining of the lungs, which
may lead to permanent changes in lung tissue and irreversible
reductions in lung function. People who are more susceptible to effects
associated with exposure to ozone include children, the elderly, and
individuals with respiratory disease such as asthma. There is also
suggestive evidence that certain people may have greater genetic
susceptibility. Those with greater exposures to ozone, for instance due
to time spent outdoors (e.g., outdoor workers), are also of concern.
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\98\ U.S. EPA, Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006. This document
is available in Docket EPA-HQ-OAR-2005-0036.
\99\ U.S. EPA (2007) Review of National Ambient Air Quality
Standards for Ozone, Assessment of Scientific and Technical
Information, OAQPS Staff Paper, EPA-452/R-07-003. This document is
available in Docket EPA-HQ-OAR-2005-0036.

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[[Page 8442]]

The recent ozone AQCD also examined relevant new scientific
information which has emerged in the past decade, including the impact
of ozone exposure on such health effects as changes in lung structure
and biochemistry, inflammation of the lungs, exacerbation and causation
of asthma, respiratory illness-related school absence, hospital
admissions and premature mortality. Animal toxicologic studies have
suggested potential interactions between ozone and PM with increased
responses observed to mixtures of the two pollutants compared to either
ozone or PM alone. The respiratory morbidity observed in animal studies
along with the evidence from epidemiologic studies supports a causal
relationship between acute ambient ozone exposures and increased
respiratory-related emergency room visits and hospitalizations in the
warm season. In addition, there is suggestive evidence of a
contribution of ozone to cardiovascular-related morbidity and non-
accidental and cardiopulmonary mortality.
3. Plant and Ecosystem Effects of Ozone
Ozone contributes to many environmental effects, with impacts to
plants and ecosystems being of most concern. Ozone can produce both
acute and chronic injury in sensitive species depending on the
concentration level and the duration of the exposure. Ozone effects
also tend to accumulate over the growing season of the plant, so that
even lower concentrations experienced for a longer duration have the
potential to create chronic stress on vegetation. Ozone damage to
plants includes visible injury to leaves and a reduction in food
production through impaired photosynthesis, both of which can lead to
reduced crop yields, forestry production, and use of sensitive
ornamentals in landscaping. In addition, the reduced food production in
plants and subsequent reduced root growth and storage below ground, can
result in other, more subtle plant and ecosystems impacts. These
include increased susceptibility of plants to insect attack, disease,
harsh weather, interspecies competition and overall decreased plant
vigor. The adverse effects of ozone on forest and other natural
vegetation can potentially lead to species shifts and loss from the
affected ecosystems, resulting in a loss or reduction in associated
ecosystem goods and services. Lastly, visible ozone injury to leaves
can result in a loss of aesthetic value in areas of special scenic
significance like national parks and wilderness areas. The final 2006
ozone AQCD presents more detailed information on ozone effects on
vegetation and ecosystems.
4. Current and Projected 8-hour Ozone Levels
Currently, ozone concentrations exceeding the level of the 8-hour
ozone NAAQS occur over wide geographic areas, including most of the
nation's major population centers.\100\ As of October 2006
approximately 157 million people live in the 116 areas that are
currently designated as not in attainment with the 8-hour ozone NAAQS.
There are 461 full or partial counties that make up the 116 8-hour
ozone nonattainment areas.
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\100\ A map of the 8-hour ozone nonattainment areas is included
in the RIA for this rule.
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EPA has already adopted many emission control programs that are
expected to reduce ambient ozone levels. These control programs include
the Clean Air Interstate Rule (70 FR 25162, May 12, 2005), as well as
many mobile source rules (many of which are described in section V.D).
As a result of these programs, the number of areas that fail to meet
the 8-hour ozone NAAQS is expected to decrease.
Based on the recent ozone modeling performed for the CAIR
analysis,\101\ barring additional local ozone precursor controls, we
estimate 37 Eastern counties (where 24 million people are projected to
live) will exceed the 8-hour ozone NAAQS in 2010. An additional 148
Eastern counties (where 61 million people are projected to live) are
expected to be within 10 percent of violating the 8-hour ozone NAAQS in
2010.
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\101\ Technical Support Document for the Final Clean Air
Interstate Rule Air Quality Modeling. This document is available in
Docket EPA-HQ-OAR-2005-0036.
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States with 8-hour ozone nonattainment areas will be required to
take action to bring these areas into compliance in the future. Based
on the final rule designating and classifying 8-hour ozone
nonattainment areas (69 FR 23951, April 30, 2004), most 8-hour ozone
nonattainment areas will be required to attain the 8-hour ozone NAAQS
in the 2007 to 2013 time frame and then be required to maintain the 8-
hour ozone NAAQS thereafter.\102\ The expected ozone inventory
reductions from the standards being finalized in this action may be
useful to states in attaining or maintaining the 8-hour ozone NAAQS.
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\102\ The Los Angeles South Coast Air Basin 8-hour ozone
nonattainment area will have to attain before June 15, 2021.
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EPA's review of the ozone NAAQS is currently underway and a
proposed decision in this review is scheduled for June 2007 with a
final rule scheduled for March 2008. If the ozone NAAQS is revised,
then new nonattainment areas could be designated. While EPA is not
relying on it for purposes of justifying this rule, the emission
reductions from this rulemaking would also be helpful to states if
there is an ozone NAAQS revision.

D. Particulate Matter

The cold temperature vehicle controls being finalized here will
result in reductions of primary PM being emitted by vehicles. In
addition, both the vehicle controls and the PFC controls will reduce
VOCs that react in the atmosphere to form secondary PM_2.5,
namely organic carbonaceous PM_2.5.
1. Background
Particulate matter (PM) represents a broad class of chemically and
physically diverse substances. It can be principally characterized as
discrete particles that exist in the condensed (liquid or solid) phase
spanning several orders of magnitude in size. PM is further described
by breaking it down into size fractions. PM₁₀ refers to
particles generally less than or equal to 10 micrometers ([mu]m) in
diameter. PM_2.5 refers to fine particles, those particles
generally less than or equal to 2.5 [mu]m in diameter. Inhalable (or
``thoracic'') coarse particles refer to those particles generally
greater than 2.5 [mu]m but less than or equal to 10 [mu]m in diameter.
Ultrafine PM refers to particles with diameters generally less than 100
nanometers (0.1 [mu]m). Larger particles (>10 [mu]m) tend to be removed
by the respiratory clearance mechanisms, whereas smaller particles are
deposited deeper in the lungs.
Fine particles are produced primarily by combustion processes and
by transformations of gaseous emissions (e.g., SO_x,
NO_X and VOCs) in the atmosphere. The chemical and physical
properties of PM_2.5 may vary greatly with time, region,
meteorology and source category. Thus, PM_2.5 may include a
complex mixture of different pollutants including sulfates, nitrates,
organic compounds, elemental carbon and metal compounds. These
particles can remain in the atmosphere for days to weeks and travel
through the atmosphere hundreds to thousands of kilometers.
EPA has recently amended the PM NAAQS (71 FR 61144, October 17,
2006). The final rule, signed on September 21, 2006 and published on
October 17, 2006, addressed revisions to the primary and secondary
NAAQS for PM to provide increased protection of public health and
welfare, respectively.

[[Page 8443]]

The primary PM_2.5 NAAQS include a short-term (24-hour) and a
long-term (annual) standard. The level of the 24-hour PM_2.5
NAAQS has been revised from 65 [mu]g/m\3\ to 35 [mu]g/m\3\ to provide
increased protection against health effects associated with short-term
exposures to fine particles. The current form of the 24-hour
PM_2.5 standard was retained (e.g., based on the 98th
percentile concentration averaged over three years). The level of the
annual PM_2.5 NAAQS was retained at 15 [mu]g/m\3\ continuing
protection against health effects associated with long-term exposures.
The current form of the annual PM_2.5 standard was retained
as an annual arithmetic mean averaged over three years, however, the
following two aspects of the spatial averaging criteria were narrowed:
(1) The annual mean concentration at each site shall be within 10
percent of the spatially averaged annual mean, and (2) the daily values
for each monitoring site pair shall yield a correlation coefficient of
at least 0.9 for each calendar quarter. With regard to the primary
PM₁₀ standards, the 24-hour PM₁₀ NAAQS was
retained at a level of 150 [mu]g/m\3\ not to be exceeded more than once
per year on average over a three-year period. Given that the available
evidence does not suggest an association between long-term exposure to
coarse particles at current ambient levels and health effects, EPA has
revoked the annual PM₁₀ standard.
With regard to the secondary PM standards, EPA has revised these
standards to be identical in all respects to the revised primary
standards. Specifically, EPA has revised the current 24-hour
PM_2.5 secondary standard by making it identical to the
revised 24-hour PM_2.5 primary standard, retained the annual
PM_2.5 and 24-hour PM₁₀ secondary standards, and
revoked the annual PM₁₀ secondary standards. This suite of
secondary PM standards is intended to provide protection against PM-
related public welfare effects, including visibility impairment,
effects on vegetation and ecosystems, and material damage and soiling.
2. Health Effects of PM
Scientific studies show ambient PM is associated with a series of
adverse health effects. These health effects are discussed in detail in
the 2004 Particulate Matter Air Quality Criteria Document (PM AQCD) as
well as the 2005 PM Staff Paper.103, 104 Further discussion
of health effects associated with PM can also be found in the RIA for
this final rule.
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\103\ U.S. EPA (2004) Air Quality Criteria for Particulate
Matter (Oct 2004), Volume I Document No. EPA600/P-99/002aF and
Volume II Document No. EPA600/P-99/002bF. This document is available
in Docket EPA-HQ-OAR-2005-0036.
\104\ U.S. EPA (2005) Review of the National Ambient Air Quality
Standard for Particulate Matter: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR-2005-0036.
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Health effects associated with short-term exposures (e.g. hours to
days) in ambient PM_2.5 include premature mortality,
increased hospital admissions, heart and lung diseases, increased
cough, adverse lower-respiratory symptoms, decrements in lung function
and changes in heart rate rhythm and other cardiac effects. Studies
examining populations exposed to different levels of air pollution over
a number of years, including the Harvard Six Cities Study and the
American Cancer Society Study, show associations between long-term
exposure to ambient PM_2.5 and both total and
cardiorespiratory mortality. In addition, the reanalysis of the
American Cancer Society cohort shows an association between fine
particle and sulfate concentrations and lung cancer mortality.
Recently, several studies have highlighted the adverse effects of
PM specifically from mobile sources.105, 106 Studies have
also focused on health effects due to PM exposures on or near
roadways.\107\ Although these studies include all air pollution
sources, including both spark-ignition (gasoline) and diesel powered
vehicles, they indicate that exposure to PM emissions near roadways,
thus dominated by mobile sources, are associated with health effects.
Additional information on near-roadway health effects can be found in
section III.B.2.d of this preamble.
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\105\ Laden, F.; Neas, L.M.; Dockery, D.W.; Schwartz, J. (2000)
Association of Fine Particulate Matter from Different Sources with
Daily Mortality in Six U.S. Cities. Environmental Health
Perspectives 108: 941-947.
\106\ Janssen, N.A.H.; Schwartz, J.; Zanobetti, A.; Suh, H.H.
(2002) Air Conditioning and Source-Specific Particles as Modifiers
of the Effect of PM₁₀ on Hospital Admissions for Heart
and Lung Disease. Environmental Health Perspectives 110: 43-49.
\107\ Riediker, M.; Cascio, W.E.; Griggs, T.R.; Herbst, M.C.;
Bromberg, P.A.; Neas, L.; Williams, R.W.; Devlin, R.B. (2003)
Particulate Matter Exposures in Cars is Associated with
Cardiovascular Effects in Healthy Young Men. Am. J. Respir. Crit.
Care Med. 169: 934-940.
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3. Welfare Effects of PM
a. Visibility
i. Background
Visibility can be defined as the degree to which the atmosphere is
transparent to visible light.\108\ Visibility impairment manifests in
two principal ways: as local visibility impairment and as regional
haze.\109\ Local visibility impairment may take the form of a localized
plume, a band or layer of discoloration appearing well above the
terrain as a result from complex local meteorological conditions.
Alternatively, local visibility impairment may manifest as an urban
haze, sometimes referred to as a ``brown cloud.'' This urban haze is
largely caused by emissions from multiple sources in the urban areas
and is not typically attributable to only one nearby source or to long-
range transport. The second type of visibility impairment, regional
haze, usually results from multiple pollution sources spread over a
large geographic region. Regional haze can impair visibility over large
regions and across states.
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\108\ National Research Council, 1993. Protecting Visibility in
National Parks and Wilderness Areas. National Academy of Sciences
Committee on Haze in National Parks and Wilderness Areas. National
Academy Press, Washington, DC. This document is available in Docket
EPA-HQ-OAR-2005-0036. This book can be viewed on the National
Academy Press Web site at http://www.nap.edu/books/0309048443/html/.

\109\ See discussion in U.S. EPA, National Ambient Air Quality
Standards for Particulate Matter; Proposed Rule; January 17, 2006,
Vol 71, p. 2676. This information is available electronically at
http://epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/a177.pdf.

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Visibility is important because it has direct significance to
people's enjoyment of daily activities in all parts of the country.
Individuals value good visibility for the well-being it provides them
directly, where they live and work, and in places where they enjoy
recreational opportunities. Visibility is also highly valued in
significant natural areas such as national parks and wilderness areas,
and special emphasis is given to protecting visibility in these areas.
For more information on visibility see the 2004 PM AQCD as well as the
2005 PM Staff Paper.110 111
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\110\ U.S. EPA (2004) Air Quality Criteria for Particulate
Matter (Oct 2004), Volume I Document No. EPA600/P-99/002aF and
Volume II Document No. EPA600/P-99/002bF. This document is available
in Docket EPA-HQ-OAR-2005-0036.
\111\ U.S. EPA (2005) Review of the National Ambient Air Quality
Standard for Particulate Matter: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR-2005-0036.
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Fine particles are the major cause of reduced visibility in parts
of the United

[[Page 8444]]

States. To address the welfare effects of PM on visibility, EPA set
secondary PM_2.5 standards which would act in conjunction
with the establishment of a regional haze program. In setting this
secondary standard, EPA concluded that PM_2.5 causes adverse
effects on visibility in various locations, depending on PM
concentrations and factors such as chemical composition and average
relative humidity. The secondary (welfare-based) PM_2.5 NAAQS
was established as equal to the suite of primary (health-based) NAAQS.
Furthermore, section 169 of the Act provides additional authorities to
remedy existing visibility impairment and prevent future visibility
impairment in the 156 national parks, forests and wilderness areas
categorized as mandatory class I federal areas (62 FR 38680-81, July
18, 1997).\112\ In July 1999 the regional haze rule (64 FR 35714) was
put in place to protect the visibility in mandatory class I federal
areas. Visibility can be said to be impaired in both PM_2.5
nonattainment areas and mandatory class I federal areas.
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\112\ These areas are defined in section 162 of the Act as those
national parks exceeding 6,000 acres, wilderness areas and memorial
parks exceeding 5,000 acres, and all international parks which were
in existence on August 7, 1977.
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ii. Current Visibility Impairment
Recently designated PM_2.5 nonattainment areas indicate
that, as of October 2006, almost 90 million people live in
nonattainment areas for the 1997 PM_2.5 NAAQS. Thus, at least
these populations would likely be experiencing visibility impairment,
as well as many thousands of individuals who travel to these areas. In
addition, while visibility trends have improved in mandatory class I
federal areas, the most recent data show that these areas continue to
suffer from visibility impairment.\113\ In summary, visibility
impairment is experienced throughout the U.S., in multi-state regions,
urban areas, and remote mandatory class I federal
areas.114 115 The mandatory class I federal areas are listed
in Chapter 3 of the RIA for this action. The areas that have design
values above the 1997 PM_2.5 NAAQS are also listed in Chapter
3 of the RIA for this action.
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\113\ U.S. EPA, Regulatory Impact Analysis for the Final Clean
Air Interstate Rule. This document is available in Docket EPA-HQ-
OAR-2005-0036.
\114\ U.S. EPA, Air Quality Designations and Classifications for
the Fine Particles (PM_2.5) National Ambient Air Quality
Standards, December 17, 2004. (70 FR 943, January 5, 2005) This
document is also available on the web at: http://www.epa.gov/pmdesignations/.
\115\ U.S. EPA, Regional Haze Regulations, July 1, 1999. (64 FR
35714, July 1, 1999)
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iii. Future Visibility Impairment
Recent modeling for the Clean Air Interstate Rule (CAIR) was used
to project visibility conditions in mandatory class I federal areas
across the country in 2015. The results for the mandatory class I
federal areas suggest that these areas are predicted to continue to
have annual average deciview levels above background in the
future.\116\ Modeling done for the PM NAAQS also projected
PM_2.5 levels in 2015. These projections include all sources
of PM_2.5, including the engines covered in this rule, and
suggest that PM_2.5 levels above the NAAQS will persist into
the future.
---------------------------------------------------------------------------

\116\ The deciview metric describes perceived visual changes in
a linear fashion over its entire range, analogous to the decibel
scale for sound. A deciview of 0 represents pristine conditions. The
higher the deciview value, the worse the visibility, and an
improvement in visibility is a decrease in deciview value.
---------------------------------------------------------------------------

The vehicles that will be subject to the standards contribute to
visibility concerns in these areas through both their primary PM
emissions and their VOC emissions, which contribute to the formation of
secondary PM_2.5. The PFCs that will be subject to the
standards also contribute to visibility concerns through their VOC
emissions. Reductions in these direct PM and VOC emissions will help to
improve visibility across the nation, including mandatory class I
federal areas.
b. Atmospheric Deposition
Wet and dry deposition of ambient particulate matter delivers a
complex mixture of metals (e.g., mercury, zinc, lead, nickel, aluminum,
cadmium), organic compounds (e.g., POM, dioxins, furans) and inorganic
compounds (e.g., nitrate, sulfate) to terrestrial and aquatic
ecosystems. EPA's Great Waters Program has identified 15 pollutants
whose deposition to water bodies has contributed to the overall
contamination loadings to these Great Waters. These 15 compounds
include several heavy metals and a group known as polycyclic organic
matter (POM). Within POM are the polycyclic aromatic hydrocarbons
(PAHs). PAHs in the environment may be present in the gas or particle
phase, although the bulk will be adsorbed onto airborne particulate
matter. In most cases, human-made sources of PAHs account for the
majority of PAHs released to the environment. The PAHs are usually the
POMs of concern as many PAHs are probable human carcinogens.\117\ For
some watersheds, atmospheric deposition represents a significant input
to the total surface water PAH burden.118 119 Emissions from
mobile sources have been found to account for a percentage of the
atmospheric deposition of PAHs. For instance, recent studies have
reported gasoline and diesel vehicles as major contributors in the
atmospheric deposition of PAHs to Chesapeake Bay, Massachusetts Bay and
Casco Bay.120 121 The vehicle controls being finalized may
help to reduce deposition of heavy metals and POM.
---------------------------------------------------------------------------

\117\ Deposition of Air Pollutants to the Great Waters--Third
Report to Congress, Office of Air Quality Planning and Standards,
June 2000, EPA453-R-00-005. This document is available in Docket
EPA-HQ-OAR-2005-0036.
\118\ Simcik, M.F.; Eisenrich, S.J.; Golden, K.A.; Liu, S.;
Lipiatou, E.; Swackhamer, D.L.; and Long, D.T. (1996) Atmospheric
Loading of Polycyclic Aromatic Hydrocarbons to Lake Michigan as
Recorded in the Sediments. Environ. Sci. Technol. 30:3039-3046.
\119\ Simcik, M.F.; Eisenrich, S.J.; and Lioy, P.J. (1999)
Source Apportionment and Source/Sink Relationships of PAHs in the
Coastal Atmosphere of Chicago and Lake Michigan. Atmospheric
Environment 33: 5071-5079.
\120\ Dickhut, R.M.; Canuel, E.A.; Gustafson, K.E.; Liu, K.;
Arzayus, K.M.; Walker, S.E.; Edgecombe, G.; Gaylor, M.O.; and
McDonald, E.H. (2000) Automotive Sources of Carcinogenic Polycyclic
Aromatic Hydrocarbons Associated with Particulate Matter in the
Chesapeake Bay Region. Environ. Sci. Technol. 34: 4635-4640.
\121\ Golomb, D.; Barry, E.; Fisher, G.; Varanusupakul, P.;
Koleda, M.; and Rooney, T. (2001) Atmospheric Deposition of
Polycyclic Aromatic Hydrocarbons near New England Coastal Waters.
Atmospheric Environment 35: 6245-6258.
---------------------------------------------------------------------------

c. Materials Damage and Soiling
The deposition of airborne particles can also reduce the aesthetic
appeal of buildings and culturally important articles through soiling,
and can contribute directly (or in conjunction with other pollutants)
to structural damage by means of corrosion or erosion.\122\ Particles
affect materials principally by promoting and accelerating the
corrosion of metals, by degrading paints, and by deteriorating building
materials such as concrete and limestone. Particles contribute to these
effects because of their electrolytic, hygroscopic, and acidic
properties, and their ability to sorb corrosive gases (principally
sulfur dioxide). The rate of metal corrosion depends on a number of
factors, including the deposition rate and nature of the pollutant; the
influence of the metal protective corrosion film; the amount of
moisture present; variability in the electrochemical reactions; the
presence and concentration of other surface electrolytes; and the
orientation of the metal surface.
---------------------------------------------------------------------------

\122\ U.S EPA (2005) Review of the National Ambient Air Quality
Standards for Particulate Matter: Policy Assessment of Scientific
and Technical Information, OAQPS Staff Paper. This document is
available in Docket EPA-HQ-OAR-2005-0036.

---------------------------------------------------------------------------

[[Page 8445]]

4. Current and Projected PM_2.5 Levels
In 2005 EPA designated 39 nonattainment areas for the 1997
PM_2.5 NAAQS based on air quality design values (using 2001-
2003 or 2002-2004 measurements) and a number of other factors.\123\
(See 70 FR 943, January 5, 2005; 70 FR 19844, April 14, 2005.) These
areas are comprised of 208 full or partial counties with a total
population exceeding 88 million. As mentioned in section III.D.1, the
1997 PM_2.5 NAAQS was recently revised and the 2006
PM_2.5 NAAQS became effective on December 18, 2006. Table
III.D-1 presents the number of counties in areas currently designated
as nonattainment for the 1997 PM_2.5 NAAQS as well as the
number of additional counties which have monitored data that is
violating the 2006 PM_2.5 NAAQS. Nonattainment areas will be
designated with respect to the new 2006 PM_2.5 NAAQS in early 2010.
---------------------------------------------------------------------------

\123\ The full details involved in calculating a
PM_2.5 design value are given in Appendix N of 40 CFR Part 50.

Table III.D-1.--PM2.5 Standards: Current Nonattainment Areas and Other
Violating Counties
------------------------------------------------------------------------
Number of
counties Population\1\
------------------------------------------------------------------------
1997 PM2.5 Standards: 39 areas currently 208 88,394,000
designated...............................
2006 PM2.5 Standards: Counties with 49 18,198,676
violating monitors \2\...................
-----------------------------
Total................................. 257 106,592,676
------------------------------------------------------------------------
\1\ Population numbers are from 2000 census data.
\2\ This table provides an estimate of the counties violating the 2006
PM2.5 NAAQS based on 2003-05 air quality data. The areas designated as
nonattainment for the 2006 PM2.5 NAAQS will be based on 3 years of air
quality data from later years. Also, the county numbers in the summary
table include only the counties with monitors violating the 2006 PM2.5
NAAQS. The monitored county violations may be an underestimate of the
number of counties and populations that will eventually be included in
areas with multiple counties designated nonattainment.

Based on modeling performed for the PM NAAQS analysis, we estimate
that 52 counties (where 53 million people are projected to live) will
exceed the 2006 PM_2.5 standard in 2015.124 125 In
addition, 54 counties (where 27 million people are projected to live)
are expected to be within 10 percent of violating the 2006
PM_2.5 NAAQS in 2015.
---------------------------------------------------------------------------

\124\ Note that this analysis identifies only counties projected
to have a violating monitor; when designated in the future, some
areas may include additional contributing counties. Thus, the total
number of counties designated in the future and the associated
population would likely exceed these estimates.
\125\ Regulatory Impact Analysis for the final PM NAAQS rule.
This document is available in Docket EPA-HQ-OAR-2005-0036.
---------------------------------------------------------------------------

Areas designated as not attaining the 1997 PM_2.5 NAAQS
will need to attain these standards in the 2010 to 2015 time frame, and
then be required to maintain the NAAQS thereafter. The attainment dates
associated with the potential nonattainment areas based on the 2006
PM_2.5 NAAQS would likely be in the 2015 to 2020 timeframe.
The emissions standards being finalized in this action would become
effective between 2009 and 2015, making the expected PM and VOC
inventory reductions useful to states in attaining or maintaining the
PM_2.5 NAAQS.
5. Current PM₁₀ Levels
Air quality monitoring data indicates that as of October 2006
approximately 28.5 million people live in 46 designated PM₁₀
nonattainment areas, which include all or part of 46 counties. The RIA
for this rule lists the PM₁₀ nonattainment areas and their
populations, as of October 2006. The expected PM and VOC inventory
reductions from the standards being finalized in this action could be
useful to states in maintaining the PM₁₀ NAAQS.

IV. What Are the Emissions, Air Quality, and Public Health Impacts of
This Rule?

A. Emissions Impacts of All Rule Provisions Combined

The emissions analysis presented in section IV.A of this preamble
is described in more detail in Chapter 2.2.2. of the RIA. The emissions
analysis has been updated since the proposal, largely to include the
effects of the recently proposed Renewable Fuels Standard, which was
required by the Energy Policy Act. The emissions analysis examines the
0.62 vol% standard but does not include the 1.3% maximum average,
because of the lead time necessary to conduct inventory modeling. Thus,
the emission reductions from highway vehicles and other sources
attributable to the fuel benzene standard are underestimated in many
areas of the country, particularly in areas where fuel benzene levels
were highest without control, such as the Northwest. This issue is
discussed in more detail in the RIA.
1. How Will MSAT Emissions Be Reduced?
Figure IV.A-1 depicts the estimated reduction in total air toxic
emissions emitted by mobile sources between 1990 and 2030, with and
without the standards being finalized in this rule. These estimates do
not include diesel PM. Trends in diesel PM emissions are discussed in
the regulatory impact analysis for this rule. Without standards being
finalized in this rule, emissions of air toxics from mobile sources
will be reduced by about 70% percent between 1990 and 2030, from about
3.3 million tons to 1.3 million tons. This will occur despite a
projected increase in vehicle miles traveled of over 100 percent, and a
projected 150% increase in nonroad activity, based on units of work
called horsepower hours. Without additional controls, air toxic
emissions from mobile sources would begin to increase after 2015.
Similar trends are observed for benzene (see Figure IV.A-2), with a
reduction in emissions from about 380,000 tons in 1990 to less than
170,000 tons in 2030, but emissions from mobile sources begin to
increase again after 2015.

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Total emissions of MSATs from mobile and stationary sources in 2030
will be 330,000 tons less than they would have been without this rule
(Figure IV.A-3). Of these 330,000 tons of reductions, 310,000 will be
from mobile sources, with the rest from portable fuel containers (PFCs)
and gasoline distribution.\126\ Table IV.A-1 summarizes MSAT reductions
by source sector in 2015, 2020, and 2030. In addition, total benzene
emissions from mobile and stationary sources will be 61,000 tons less
than they would have been without this rule (Figure IV.A-4). Table
IV.A-2 depicts reductions in benzene by source sector from this rule.
---------------------------------------------------------------------------

\126\ Reduction in fuel benzene will reduce emissions through
the whole distribution chain.
---------------------------------------------------------------------------

In 2030, annual benzene emissions from gasoline on-road mobile
sources will be 45% lower as a result of this rule (Figure IV.A-5), and
over 60% lower than they were in 1999. In addition, benzene emissions
from gasoline nonroad equipment will be 14% lower in 2030, and over 45%
lower than they were in 1999. Benzene emissions from PFCs will be
reduced by almost 80% in 2030 (Figure IV.A-6), and benzene emissions
from gasoline distribution by over 30% in 2030. For total MSAT
emissions from on-road mobile sources, there will be a 38% reduction in
MSAT emissions in 2030 (Figure IV.A-7), and a 65% reduction from 1999
levels.
Table IV.A-3 provides estimated reductions in emissions from
individual MSATs in 2015, 2020 and 2030, from gasoline vehicles,
gasoline nonroad engines, and PFCs as a result of the controls being
finalized in this rule.

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Table IV.A-1.--Estimated Reductions in MSAT Emissions From All Control Measures by Sector, 2015 to 2030
--------------------------------------------------------------------------------------------------------------------------------------------------------
2015 2020 2030
--------------------------------------------------------------------------------------------------------------
MSAT 1999 Without Without Without
rule With rule Reduction rule With rule Reduction rule With rule Reduction
(tons) (tons) (tons) (tons) (tons) (tons) (tons) (tons) (tons)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gasoline Onroad Mobile 1,452,739 675,781 558,666 117,115 693,189 507,782 185,408 808,141 505,074 303,067
Sources.....................
Gasoline Nonroad Mobile 806,725 449,422 443,973 5,449 406,196 400,816 5,380 412,617 406,856 5,761
Sources.....................
PFCs......................... 37,166 27,355 9,893 17,462 29,338 10,672 18,666 33,430 12,264 21,166
Gasoline Distribution........ 57,765 62,870 62,059 811 64,942 64,092 850 64,942 64,092 850
--------------------------------------------------------------------------------------------------------------------------
Total.................... 2,354,395 1,215,428 1,074,591 140,837 1,193,665 983,362 210,303 1,319,130 988,286 330,844
--------------------------------------------------------------------------------------------------------------------------------------------------------

Table IV.A-2.--Estimated Reductions in Benzene Emissions from All Control Measures by Sector, 2015 to 2030
--------------------------------------------------------------------------------------------------------------------------------------------------------
2015 2020 2030
--------------------------------------------------------------------------------------------------------------
Benzene 1999 Without Without Without
rule With rule Reduction rule With rule Reduction rule With rule Reduction
(tons) (tons) (tons) (tons) (tons) (tons) (tons) (tons) (tons)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gasoline Onroad Mobile 183,660 97,789 71,688 26,101 101,514 65,878 35,636 119,016 65,601 53,415
Sources.....................
Gasoline Nonroad Mobile 68,589 41,343 35,825 5,518 40,161 34,717 5,444 42,994 37,167 5,827
Sources.....................
PFCs......................... 853 992 215 777 1,063 232 831 1,210 267 944
Gasoline Distribution........ 1,984 2,445 1,635 810 2,621 1,772 849 2,621 1,772 849
--------------------------------------------------------------------------------------------------------------------------
Total.................... 255,086 142,569 109,363 33,206 145,359 102,599 42,760 165,841 104,807 61,035
--------------------------------------------------------------------------------------------------------------------------------------------------------

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Table IV.A-3.--Estimated Reductions in Emissions From Individual MSATs in 2015, 2020 and 2030, From Gasoline Vehicles, Gasoline Nonroad Engines, and
Portable Fuel Containers, Resulting From the Cumulative Impacts of the Controls in This Rule \127\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2015 2020 2030
1999 --------------------------------------------------------------------------------------------------------------
MSAT (tons) Without With rule Reductions Without With rule Reductions Without With rule Reductions
rule (tons) (tons) (tons) rule (tons) (tons) (tons) rule (tons) (tons) (tons)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1,3-Butadiene................ 31,234 14,771 13,259 1,512 15,037 12,535 2,501 17,054 12,834 4,220
2,2,4-Trimethylpentane....... 296,310 166,270 149,178 17,091 159,892 133,578 26,314 174,824 132,763 42,061
Acetaldehyde................. 27,800 21,223 18,154 3,069 22,156 17,011 5,145 25,754 17,213 8,541
Acrolein..................... 3,835 1,650 1,457 193 1,665 1,347 317 1,889 1,360 529
Benzene...................... 250,227 140,124 107,728 32,396 142,737 100,827 41,911 163,221 103,035 60,186
Ethyl Benzene................ 120,150 61,300 54,805 6,495 59,963 49,968 9,995 66,823 50,830 15,992
Formaldehyde................. 74,053 32,341 28,096 4,245 33,350 26,371 6,979 38,472 26,946 11,526
Hexane....................... 106,464 57,852 52,042 5,810 54,673 46,926 7,747 59,152 48,029 11,124
MTBE......................... 143,350 0 0 0 0 0 0 0 0 0
Propionaldehyde.............. 4,142 2,195 1,965 231 2,249 1,869 380 2,565 1,932 633
Styrene...................... 16,352 8,212 6,985 1,227 8,423 6,405 2,018 9,731 6,365 3,366
Toluene...................... 729,908 390,688 347,363 43,325 380,420 312,542 67,878 420,534 310,654 109,880
Xylenes...................... 487,768 252,993 228,561 24,432 245,180 206,913 38,267 270,775 208,839 61,936
--------------------------------------------------------------------------------------------------------------------------
Total MSATs.............. 2,291,593 1,149,618 1,009,592 140,026 1,125,744 916,291 209,453 1,250,794 920,800 329,994
--------------------------------------------------------------------------------------------------------------------------------------------------------

2. How Will VOC Emissions Be Reduced?
---------------------------------------------------------------------------

\127\ Napthalene reductions from controls in this rule are not
quantified, due to limitations in modeling tools.
---------------------------------------------------------------------------

VOC emissions will be reduced by the hydrocarbon emission standards
for both light-duty vehicles and PFCs. As seen in the table and
accompanying figure below Table IV.A-4 and Figure IV.A-8, annual VOC
emission reductions from both of these sources will be 34% lower in
2030 because of this rule, and 59% lower than in 1999.

[[Page 8453]]

Table IV.A-4. Estimated Reductions in VOC Emissions from Light-Duty Gasoline Vehicles and PFCs, 1999 to 2030
----------------------------------------------------------------------------------------------------------------
1999 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
VOC Without Rule (tons)..................................... 5,224,921 2,944,491 2,892,134 3,281,752
VOC With Vehicle and PFC Standards (tons)................... ........... 2,420,860 2,146,476 2,153,735
VOC Reduction (tons)........................................ ........... 523,631 745,658 1,128,017
----------------------------------------------------------------------------------------------------------------

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3. How Will PM Emissions Be Reduced?
EPA expects that the cold-temperature vehicle standards will reduce
exhaust emissions of direct PM_2.5 by over 19,000 tons in
2030 nationwide (see Table IV.A-5 below). Our analysis of the data from
vehicles meeting Tier 2 emission standards indicate that PM emissions
follow a monotonic relationship with temperature, with lower
temperatures corresponding to higher vehicle emissions. Additionally,
the analysis shows the ratio of PM to total non-methane hydrocarbons
(NMHC) to be independent of temperature.\128\ Our testing indicates
that strategies which reduce NMHC start emissions at cold temperatures
also reduce direct PM emissions. Based on these findings, direct PM
emissions at cold temperatures were estimated using a constant PM to
NMHC ratio. PM emission reductions were estimated by assuming that NMHC
reductions will result in proportional reductions in PM. This
assumption is supported by test data. For more detail, see Chapter 2.1
of the RIA.
---------------------------------------------------------------------------

\128\ U.S. EPA. 2005. Cold-temperature exhaust particulate
matter emissions. Memorandum from Chad Bailey to docket EPA-HQ-OAR-
2005-0036.

Table IV.A-5. Estimated National Reductions in Direct PM2.5 Exhaust
Emissions From Light-Duty Gasoline Vehicles and Trucks, 2015 to 2030
------------------------------------------------------------------------
2015 2020 2030
------------------------------------------------------------------------
PM2.5 Reductions from Vehicle Standards 7,068 11,646 19,421
(tons)................................
------------------------------------------------------------------------

[[Page 8454]]

B. Emission Impacts by Provision

1. Vehicle Controls
We are finalizing a hydrocarbon standard for gasoline passenger
vehicles at cold temperatures. This standard will reduce VOC at
temperatures below 75 [deg]F, including air toxics such as benzene,
1,3-butadiene, formaldehyde, acetaldehyde, and acrolein, and will also
reduce emissions of direct and secondary PM. We are also finalizing new
evaporative emissions standards for Tier 2 vehicles starting in 2009.
These new evaporative standards reflect the emissions levels already
being achieved by manufacturers.
a. Volatile Organic Compounds (VOC)
Table IV.B-1 shows the VOC exhaust emission reductions from light-
duty gasoline vehicles and trucks that will result from the cold
temperature hydrocarbon standard alone. The standards will reduce VOC
emissions from these vehicles in 2030 by 31%. Overall VOC emissions
from these vehicles will be reduced by 82% between 1999 and 2030
(including the effects of these standards as well as other standards in
place, such as Tier 2).

Table IV.B.-1. Estimated National Reductions in Exhaust VOC Emissions From Light-Duty Gasoline Vehicles and
Trucks, 1999 to 2030.
----------------------------------------------------------------------------------------------------------------
1999 2010 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
VOC Without Rule (tons)................... 4,899,891 2,990,760 2,614,987 2,538,664 2,878,836
VOC With Proposed Vehicle Standards (tons) ............ 2,839,012 2,293,703 2,009,301 1,996,074
VOC Reductions from Vehicle Standards ............ 151,748 321,284 529,363 882,762
(tons)...................................
Percentage Reduction...................... ............ 5 12 21 31
----------------------------------------------------------------------------------------------------------------

b. Toxics
In 2030, we estimate that the vehicle standards will result in a
38% reduction in total emissions of the MSATs and a 39% reduction in
benzene emissions from light-duty vehicles and trucks (see Tables IV.B-
1 and IV.B-2). Between 1999 and 2030, total MSATs from light-duty
gasoline vehicles and trucks will be reduced by 64%, and benzene by 59%.

Table IV.B.-1. Estimated National Reductions in Exhaust MSAT Emissions From Light-Duty Gasoline Vehicles and
Trucks, 1999 to 2030
----------------------------------------------------------------------------------------------------------------
1999 2010 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
MSATs Without Rule (tons)................. 1,376,002 695,408 650,012 669,707 783,648
MSATs With Vehicle Standards (tons)....... ............ 644,312 542,281 492,700 488,824
MSAT Reductions from Vehicle Standards ............ 51,987 107,731 177,007 294,824
(tons)...................................
Percentage Reduction...................... ............ 7 17 26 38
----------------------------------------------------------------------------------------------------------------

Table IV.B-2.--Estimated National Reductions in Benzene Exhaust Emissions From Light-Duty Gasoline Vehicles and
Trucks, 1999 to 2030.
----------------------------------------------------------------------------------------------------------------
1999 2010 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
Benzene Without Rule (tons)......................... 173,474 99,559 95,234 99,225 116,742
Benzene With Vehicle Standards (tons)............... .......... 91,621 78,664 72,128 71,704
Benzene Reductions from Vehicle Standards (tons).... .......... 7,939 16,570 27,097 45,037
Percentage Reduction................................ .......... 8 17 27 39
----------------------------------------------------------------------------------------------------------------

c. PM_2.5
As discussed in Section IV.A.3, EPA expects that the cold-
temperature vehicle standards will reduce exhaust emissions of direct
PM_2.5 by over 19,000 tons in 2030 nationwide (see Table IV.A-5).
2. Fuel Benzene Standard
The fuel benzene standard will reduce benzene exhaust and
evaporative emissions from both on-road and nonroad mobile sources that
are fueled by gasoline. In addition, the fuel benzene standard will
reduce evaporative emissions from gasoline distribution and PFCs.
Impacts on 1,3-butadiene, formaldehyde, and acetaldehyde emissions are
not significant, but are presented in Chapter 2 of the RIA. We do not
expect the fuel benzene standard to have quantifiable impacts on any
other air toxics, total VOCs, or direct PM.
Table IV.B-3 shows national estimates of total benzene emissions
from these source sectors with and without the fuel benzene standard in
2015. These estimates do not include effects of the vehicle or PFC
standards (see section IV.A.1 for the combined effects of the
controls). They also assume that the fuel program is fully phased in,
which is a simplification of the actual phase-in. The fuel benzene
standard will reduce total benzene emissions from on-road and nonroad
gasoline mobile sources, PFCs, and gasoline distribution by 12% in 2015.

[[Page 8455]]

Table IV.B-3.--Estimated Reductions in Benzene Emissions From Gasoline Standard by Sector in 2015
----------------------------------------------------------------------------------------------------------------
Gasoline Gasoline
on-road nonroad Gasoline
mobile mobile PFCs distribution Total
sources sources
----------------------------------------------------------------------------------------------------------------
Benzene Without Rule (tons)....................... 97,789 41,343 992 2,445 142,569
Benzene With Gasoline Standard (tons)............. 86,875 35,825 619 1,635 124,954
Benzene Reductions from Gasoline Standard (tons).. 10,914 5,518 373 810 17,615
Percentage Reduction.............................. 11 13 38 33 12
----------------------------------------------------------------------------------------------------------------

3. PFC Standards
a. VOC
Table IV.B-4 shows the reductions in VOC emissions that we expect
from the PFC standard. In 2015, VOC emissions From PFCs will be reduced
by 61% because of reduced permeation, spillage, and evaporative losses.

Table IV.B-4.--Estimated National Reductions in VOC Emissions From PFCs, 1999 to 2030
----------------------------------------------------------------------------------------------------------------
1999 2010 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
VOC Without Rule (tons)............................. 325,030 316,756 329,504 353,470 402,916
VOC With PFC Standard (tons)........................ .......... 256,175 127,157 137,175 216,294
VOC Reductions from PFC Standard (tons)............. .......... 60,580 202,347 216,294 245,255
Percentage Reduction................................ .......... 19 61 61 61
----------------------------------------------------------------------------------------------------------------

b. Toxics
The PFC standard will reduce emissions of benzene, toluene,
xylenes, ethylbenzene, n-hexane, 2,2,4-trimethylpentane, and MTBE. We
estimate that benzene emissions from PFCs will be reduced by 68% (see
Table IV.B-5) and, more broadly, air toxic emissions by 63% (see Table
IV.B-6) in year 2015. These reductions do not include effects of the
fuel benzene standard (see section IV.A-1 for the combined effects of
the controls). Chapter 2 of the RIA provides details on the emission
reductions of the other toxics.

Table IV.B-5.--Estimated National Reductions in Benzene Emissions From PFCs, 1999 to 2030
----------------------------------------------------------------------------------------------------------------
1999 2010 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
Benzene Without Rule (tons)........................................ 853 943 992 1063 1210
Benzene With PFC Standard (tons)................................... ....... 743 320 345 396
Benzene Reductions from PFC Standard (tons)........................ ....... 200 672 718 814
Percentage Reduction............................................... ....... 21 68 68 67
----------------------------------------------------------------------------------------------------------------

Table IV.B-6.--Estimated National Reductions in Total MSAT Emissions From PFCs, 1999 to 2030
----------------------------------------------------------------------------------------------------------------
1999 2010 2015 2020 2030
----------------------------------------------------------------------------------------------------------------
MSATs Without Rule (tons).......................................... 37,167 26,189 27,355 29,338 33,430
MSATs With PFC Standard (tons)..................................... ....... 21,010 9,998 10,785 12,394
MSAT Reductions from PFC Standard (tons)........................... ....... 5,179 17,357 18,553 21,036
Percentage Reduction............................................... ....... 20 63 63 63
----------------------------------------------------------------------------------------------------------------

C. What Are the Air Quality, Exposure, and Public Health Impacts of
This Rule?

1. Mobile Source Air Toxics
The controls being finalized in this rule will reduce both
evaporative and exhaust emissions from motor vehicles and nonroad
equipment. They will also reduce emissions from PFCs and stationary
source emissions associated with gasoline distribution. Therefore, they
will reduce exposure to mobile source air toxics for the general
population, and also for people near roadways, in vehicles, in homes
with attached garages, operating nonroad equipment, and living or
working near sources of gasoline distribution emissions (such as bulk
terminals, bulk plants, tankers, marine vessels, and service stations).
Section III.B of this preamble and Chapter 3 of the RIA provide more
details on these types of exposures.
We performed national-scale air quality, exposure, and risk
modeling in order to quantitatively assess the impacts of the standards
being finalized. The exposure modeling for the final rule accounted for
the spatial variability of outdoor concentrations of air toxics due to
higher concentrations near roadways. This is a significant improvement
over exposure modeling done for the proposal, and is discussed in more
detail in Chapter 3 of the RIA. However, in addition to the limitations
of the national-scale modeling tools (discussed in Chapter 3 of the
RIA), this modeling did not account for the impacts of the recently
proposed renewable fuel standard, as this standard was proposed
subsequent to the development of inventories for air quality modeling.
In addition, while the model includes the

[[Page 8456]]

0.62 vol% fuel benzene standard, it does not include the 1.3% maximum
average.
The standards being finalized in this rule will reduce both the
number of people above the 1 in 100,000 cancer risk level, and the
average population cancer risk, by reducing exposures to mobile source
air toxics. The number of people above the 1 in 100,000 cancer risk
level due to exposure to all mobile source air toxics from all sources
will decrease by over 11 million in 2020 and by almost 17 million in
2030. The number of people above the 1 in 100,000 cancer risk level
from exposure to benzene from all sources will decrease by about 30
million in 2020 and 46 million in 2030. It should be noted that if it
were possible to estimate impacts of the standard on ``background''
concentrations \129\, the estimated overall risk reductions would be
even larger. The standards will also reduce the number of people with a
respiratory hazard index (HI) greater than one by about 10 million in
2020, and 17 million in 2030. As previously discussed, a value of the
HI greater than 1.0 can be best described as indicating that a
potential may exist for adverse health effects.
---------------------------------------------------------------------------

\129\ ``Background represents the contribution to ambient levels
of air toxics from sources further away than 50 kilometers, as well
as the contribution from uninventoried sources.
---------------------------------------------------------------------------

Figure IV.C-1 depicts the impact on the mobile source contribution
to nationwide average population cancer risk from total MSATs and
benzene in 2030. Nationwide, the cancer risk attributable to total
MSATs will be reduced by 30%, and the risk from mobile source benzene
will be reduced by 37%. In 2030, the highway vehicle contribution to
MSAT cancer risk will be reduced on average 36% across the U.S., and
the highway vehicle contribution to benzene cancer risk will be reduced
on average by 43% across the U.S. The methods and assumptions used to
model the impact of the controls are described in more detail in
Chapter 3 of the RIA.
Figure IV.C-2 depicts the impact on the mobile source contribution
to nationwide average respiratory hazard index (HI) in 2030.
Nationwide, the mobile source contribution to the respiratory hazard
index will be reduced by 23%.
[GRAPHIC]
[TIFF OMITTED] TR26FE07.008
[[Page 8457]]
[GRAPHIC]
[TIFF OMITTED] TR26FE07.009

Table IV.C-1 summarizes the change in median and 95th percentile
inhalation cancer risks from benzene and all MSATs attributable to all
outdoor sources in 2015, 2020, and 2030, with the controls being
finalized in this rule. The reductions in risk would be larger if the
modeling fully accounted for a number of factors, including exposure to
benzene emissions from vehicles, equipment, and PFCs in attached
garages and the impacts of the control program on ``background'' levels
attributable to transport. Reductions are significantly larger for
individuals in the 95th percentile than in the 50th percentile. Thus,
this rule is providing bigger benefits to individuals experiencing the
highest levels of risk.

Table IV.C--1. Change in Median and 95th Percentile Inhalation Cancer Risk from Benzene and All MSATs Attributable to Outdoor Sources in 2015, 2020, and
2030 With the Controls Being Finalized in This Rule
--------------------------------------------------------------------------------------------------------------------------------------------------------
2015 2020 2030
-----------------------------------------------------------------------------------------------------
Median 95th Median 95th Median 95th
--------------------------------------------------------------------------------------------------------------------------------------------------------
All MSATs:
Without Controls.............................. 1.50x10-\5\ 4.75x10-\5\ 1.53x10-\5\ 4.93x10-\5\ 1.61x10-\5\ 5.28x10-\5\
With Controls................................. 1.41x10-\5\ 4.37x10-\5\ 1.40x10-\5\ 4.40x10-\5\ 1.42x10-\5\ 4.49x10-\5\
Percent Change................................ 6 8 8 11 12 15
Benzene:
Without Controls.............................. 6.86x10-\6\ 1.82x10-\5\ 6.93x10-\6\ 1.86x10-\5\ 7.37x10-\6\ 2.06x10-\5\
With Controls................................. 6.17x10-\6\ 1.53x10-\5\ 6.02x10-\6\ 1.47x10-\5\ 6.06x10-\6\ 1.49x10-\5\
Percent Change................................ 10 16 13 21 18 28
--------------------------------------------------------------------------------------------------------------------------------------------------------

2. Ozone
The vehicle and PFC standards will also reduce VOC emissions, which
are a precursor to ozone. We have modeled the ozone impacts of the PFC
standards. As described in more detail in Chapter 3.3 of the RIA, a
metamodeling tool developed at EPA, the ozone response surface
metamodel, was used to estimate the effects of the emission reductions.
The ozone response surface metamodel was created using multiple runs of
the Comprehensive Air Quality Model with Extensions (CAMx). Base and
control CAMx metamodeling was completed for two future years (2020,
2030) over a modeling domain that includes all or part of 37 Eastern
U.S. states. For more information on the response surface metamodel,
please see the RIA for this final rule or the Air Quality Modeling
Technical Support Document (TSD).
We have made estimates using the ozone response surface metamodel
to illustrate the types of change in future ozone levels that we would
expect to result from this rule, as described in Chapter 3 of the RIA.
The PFC controls are projected to result in a very small

[[Page 8458]]

net improvement in future ozone, after weighting for population.
Although the net future ozone improvement is small, some VOC-limited
areas in the Eastern U.S. are projected to have non-negligible
improvements in projected 8-hour ozone design values due to the PFC
controls. We view these improvements as useful in meeting the 8-hour
ozone NAAQS. These net ozone improvements are in addition to reductions
in levels of benzene, a toxic ozone precursor, due to the PFC controls.
3. PM
As described in section IV.A, the vehicle standards will reduce
emissions of direct PM. The PM health benefits that would be associated
with these reductions in PM emissions and exposure are discussed in
section VIII.E of this preamble. The vehicle and PFC standards will
also reduce VOC emissions, which contribute to the secondary formation
of PM. In this rule we have not quantified the impact of the VOC
emission reductions on ambient PM or associated health effects.

D. What Other Mobile Source Emissions Control Programs Reduce MSATs?

As described in section IV.A, existing mobile source control
programs in combination with this rule will reduce MSAT emissions (not
including diesel PM) by 45% between 1999 and 2030. The existing mobile
source programs include controls on fuels, highway vehicles, and
nonroad engines and equipment. These programs are also reducing
hydrocarbons and PM more generally, as well as oxides of nitrogen. The
sections immediately below provide general descriptions of these
programs that will be providing MSAT emission reductions, as well as
voluntary programs such as the National Clean Diesel Campaign and Best
Workplaces for Commuters. We also discuss some programs that are
currently being developed. A more detailed description of mobile source
programs is provided in Chapter 2 of the RIA.
1. Fuels Programs
As described in section VI of this preamble, this rule would
supersede the 2001 MSAT rule and certain provisions of the reformulated
gasoline program and anti-dumping programs. These programs are
described in Chapter 2 of the RIA.
a. Gasoline Sulfur
EPA's gasoline sulfur program \130\ requires, beginning in 2006,
that sulfur levels in gasoline could be no higher than 80 ppm as a per-
gallon cap, and must average 30 ppm annually. When fully effective,
gasoline will have 90 percent less sulfur than before the program.
Reduced sulfur levels are necessary to ensure that vehicle emission
control systems are not impaired. These systems effectively reduce non-
methane organic gas (NMOG) emissions, of which some are air toxics, as
well as emissions of NO_X. With lower sulfur levels, emission
control technologies can work longer and more efficiently. Both new and
older vehicles benefit from reduced gasoline sulfur levels.
---------------------------------------------------------------------------

\130\ 65 FR 6822 (February 10, 2000).
---------------------------------------------------------------------------

b. Gasoline Volatility
A fuel's volatility defines its evaporation characteristics. A
gasoline's volatility is commonly referred to as its Reid vapor
pressure, or RVP. Gasoline summertime RVP ranges from about 6-9 psi,
and wintertime RVP ranges from about 9-14 psi, when additional
volatility is required for starting in cold temperatures. Gasoline
vapors contain a subset of the liquid gasoline components, and thus can
contain toxics compounds such as benzene. Since 1989, EPA has
controlled summertime gasoline RVP primarily as a VOC and ozone
precursor control, resulting in additional toxics pollutant reductions.
c. Diesel Fuel
In early 2001, EPA issued rules requiring that diesel fuel for use
in highway vehicles contain no more than 15 ppm sulfur beginning June
1, 2006.\131\ This program contains averaging, banking and trading
provisions during the transition to the 15 ppm level, as well as other
compliance flexibilities. In June 2004, EPA issued rules governing the
sulfur content of diesel fuel used in nonroad diesel engines.\132\ In
the nonroad rule, sulfur levels are limited to a maximum of 500 ppm
sulfur beginning in 2007 (current levels are approximately 3000 ppm).
In 2010, nonroad diesel sulfur levels must not exceed 15 ppm.
---------------------------------------------------------------------------

\131\ 66 FR 5002, January 18, 2001. See
http://www.epa.gov/otaq/highway-diesel/index.htm.
\132\ 69 FR 38958, June 29, 2004.
---------------------------------------------------------------------------

EPA's diesel fuel requirements are part of a comprehensive program
to combine engine and fuel controls to achieve the greatest emission
reductions. The diesel fuel provisions enable the use of advanced
emission-control technologies on diesel vehicles and engines. The
diesel fuel requirements will also provide immediate public health
benefits by reducing PM emissions from current diesel vehicles and engines.
d. Phase-Out of Lead in Gasoline
One of the first programs to control toxic emissions from motor
vehicles was the removal of lead from gasoline. Beginning in the mid-
1970s, unleaded gasoline was phased in to replace leaded gasoline. The
phase-out of leaded gasoline was completed January 1, 1996, when lead
was banned from motor vehicle gasoline. The removal of lead from
gasoline has essentially eliminated on-highway mobile source emissions
of this highly toxic substance.
2. Highway Vehicle and Engine Programs
The 1990 Clean Air Act Amendments set specific emission standards
for hydrocarbons and for PM. Air toxics are present in both of these
pollutant categories. As vehicle manufacturers develop technologies to
comply with the hydrocarbon (HC) and particulate standards (e.g., more
efficient catalytic converters), air toxics are reduced as well. Since
1990, we have developed a number of programs to address exhaust and
evaporative hydrocarbon emissions and PM emissions.
Two of our recent initiatives to control emissions from motor
vehicles and their fuels are the Tier 2 control program for light-duty
vehicles and the 2007 heavy-duty engine rule. Together these two
initiatives define a set of comprehensive standards for light-duty and
heavy-duty motor vehicles and their fuels. In both of these
initiatives, we treat vehicles and fuels as a system. The Tier 2
control program establishes stringent tailpipe and evaporative emission
standards for light-duty vehicles and a reduction in sulfur levels in
gasoline fuel beginning in 2004.\133\ The 2007 heavy-duty engine rule
establishes stringent exhaust emission standards for new heavy-duty
engines and vehicles for the 2007 model year as well as reductions in
diesel fuel sulfur levels starting in 2006.\134\ Both of these programs
will provide substantial emissions reductions through the application
of advanced technologies. We expect 90% reductions in PM from new
diesel engines compared to engines under current standards.
---------------------------------------------------------------------------

\133\ 65 FR 6697, February 10, 2000.
\134\ 66 FR 5002, January 18, 2001.
---------------------------------------------------------------------------

Some of the key earlier programs controlling highway vehicle and
engine emissions are the Tier 1 and NLEV standards for light-duty
vehicles and trucks; enhanced evaporative emissions standards; the
supplemental federal test procedures (SFTP); urban bus standards;

[[Page 8459]]

and heavy-duty diesel and gasoline standards for the 2004/2005 time frame.
3. Nonroad Engine Programs
There are various categories of nonroad engines, including land-
based diesel engines (e.g., farm and construction equipment), small
land-based spark-ignition (SI) engines (e.g., lawn and garden
equipment, string trimmers), large land-based SI engines (e.g.,
forklifts, airport ground service equipment), marine engines (including
diesel and SI, propulsion and auxiliary, commercial and recreational),
locomotives, aircraft, and recreational vehicles (off-road motorcycles,
``all terrain'' vehicles and snowmobiles). Chapter 2 of the RIA
provides more information about these programs.
As with highway vehicles, the VOC standards we have established for
nonroad engines will also significantly reduce VOC-based toxics from
nonroad engines. In addition, the standards for diesel engines (in
combination with the stringent sulfur controls on nonroad diesel fuel)
will significantly reduce diesel PM and exhaust organic gases, which
are mobile source air toxics.
In addition to the engine-based emission control programs described
below, fuel controls will also reduce emissions of air toxics from
nonroad engines. For example, restrictions on gasoline formulation (the
removal of lead, limits on gasoline volatility and RFG) are projected
to reduce nonroad MSAT emissions because most gasoline-fueled nonroad
vehicles are fueled with the same gasoline used in on-highway vehicles.
An exception to this is lead in aviation gasoline. Aviation gasoline,
used in general (as opposed to commercial) aviation, is a high octane
fuel used in a relatively small number of aircraft (those with piston
engines). Such aircraft are generally used for personal transportation,
sightseeing, crop dusting, and similar activities.
4. Voluntary Programs
In addition to the fuel and engine control programs described
above, we are actively promoting several voluntary programs to reduce
emissions from mobile sources, such as the National Clean Diesel
Campaign, anti-idling measures, and Best Workplaces for Commuters
SM. While the stringent emissions standards described above
apply to new highway and nonroad diesel engines, it is also important
to reduce emissions from the existing fleet of about 11 million diesel
engines. EPA has launched a comprehensive initiative called the
National Clean Diesel Campaign, one component of which is to promote
the reduction of emissions in the existing fleet of engines through a
variety of cost-effective and innovative strategies. The goal of the
Campaign is to reduce emissions from the 11 million existing engines by
2014. Emission reduction strategies include switching to cleaner fuels,
retrofitting engines through the addition of emission control devices
and engine replacement. For example, installing a diesel particulate
filter achieves diesel particulate matter reductions of approximately
90 percent (when combined with the use of ultra low sulfur diesel
fuel). The Energy Policy Act of 2005 includes grant authorizations and
other incentives to help facilitate voluntary clean diesel actions
nationwide.
The National Clean Diesel Campaign is focused on leveraging local,
state, and federal resources to retrofit or replace diesel engines,
adopt best practices and track and report results. The Campaign targets
five key sectors: school buses, ports, construction, freight and
agriculture. Almost 300 clean diesel projects have been initiated
through the Campaign. These projects will reduce more than 20,000 PM
lifetime tons. PM and NO_X reductions from these programs
will provide nearly $5 billion in health benefits.
Reducing vehicle idling provides important environmental benefits.
As a part of their daily routine, truck drivers often keep their
vehicles running at idle during stops to provide power, heat and air
conditioning. EPA's SmartWay SM Transport Partnership is
helping the freight industry to adopt innovative idle reduction
technologies and to take advantage of proven systems that provide
drivers with basic necessities without idling the main engine. To date,
there are 80 mobile and stationary idle-reduction projects throughout
the country. Emission reductions, on an annual basis, from these
programs are in excess of 157,000 tons of CO₂, 2,000 tons of
NO_X and 60 tons of PM; over 14 million gallons of fuel are
being saved annually. The SmartWay Transport Partnership also works
with the freight industry by promoting a wide range of new technologies
such as advanced aerodynamics, single-wide tires, weight reduction,
speed control and intermodal shipping.
Daily commuting represents another significant source of emissions
from motor vehicles. EPA's Best Workplaces for Commuters SM
program is working with employers across the country to reverse the
trend of longer, single-occupancy vehicle commuting. OTAQ recognizes
employers that have met the National Standard of Excellence for
Commuter Benefits by adding them to the List of Best Workplaces for
Commuters. These companies offer superior commuter benefits such as
transit subsidies for rail, bus, and vanpools and promote flexi-place
and telework. Emergency Ride Home programs provide a safety net for
participants. More than 1,600 employers representing 3.5 million U.S.
workers have been designated Best Workplaces for Commuters.
Much of the growth in the Best Workplaces for Commuters program has
been through metro area-wide campaigns. Since 2002, EPA has worked with
coalitions in over 14 major metropolitan areas to increase the
penetration of commuter benefits in the marketplace and the visibility
of the companies that have received this distinguished designation.
Another significant path by which the program has grown is through
Commuter Districts including corporate and industrial business parks,
shopping malls, business improvement districts and downtown commercial
areas. To date EPA has granted the Best Workplaces for Commuters
``District'' designation to over twenty locations across the country
including sites in downtown Denver, Houston, Minneapolis, Tampa and
Boulder.
5. Additional Programs Under Development That Will Reduce MSATs
a. On-Board Diagnostics for Heavy-Duty Vehicles Over 14,000 Pounds
The Agency has proposed on-board diagnostics (OBD) requirements for
heavy-duty vehicles over 14,000 pounds.\135\ In general, OBD systems
monitor the operation of key emissions controls to detect any failure
that would lead to emissions above the standards during the life of the
vehicle. Given the nature of the heavy-duty trucking industry, 50-state
harmonization of emissions requirement is an important consideration.
Initially, the Agency signed a Memorandum of Agreement in 2004 with the
California Air Resources Board which expressed both agencies' interest
in working towards a single, nationwide program for heavy-duty OBD.
Since that time, California has established their heavy-duty OBD
program, which will begin implementation in 2010. EPA's program will
also begin in 2010. These requirements will help ensure that the
emission reductions we projected in the 2007 rulemaking for heavy-duty
engines occur in-use.
---------------------------------------------------------------------------

\135\ http://epa.gov/obd/regtech/heavy.htm.

---------------------------------------------------------------------------

[[Page 8460]]

b. Standards for Small Nonroad Spark-Ignition Engines
We are developing a proposal for small nonroad spark-ignition
engines, those typically used in lawn and garden equipment and in
spark-ignition marine engines. This proposal is being developed in
response to Section 428 of the Omnibus Appropriations Bill for 2004,
which requires EPA to propose regulations under Clean Air Act section
213 for new nonroad spark-ignition engines under 50 horsepower. We plan
to propose standards that would further reduce engine and equipment
emissions for these nonroad categories. We anticipate that any new
standards would provide significant additional reductions in exhaust
and evaporative HC (and VOC-based toxics) emissions.
c. Standards for Locomotive and Marine Diesel Engines
We are planning to propose more stringent standards for large
diesel engines used in locomotive and marine applications, as discussed
in a recent Advance Notice of Proposed Rulemaking.\136\ New standards
for marine diesel engines would apply to engines less than 30 liters
per cylinder in displacement (all engines except for Category 3). We
are considering standards modeled after our Tier 4 nonroad diesel
engine program, which achieve substantial reductions in PM, HC, and
NO_X emissions. These standards would be based on the use of
high efficiency catalyst aftertreatment and would also require fuel
sulfur control.
---------------------------------------------------------------------------

\136\ 69 FR 39276, June 29, 2004.
---------------------------------------------------------------------------

E. How Do These Mobile Source Programs Satisfy the Requirements of
Clean Air Act Section 202(l)?

The benzene and hydrocarbon standards in this action will reduce
benzene, 1,3-butadiene, formaldehyde, acrolein, polycyclic organic
matter, and naphthalene, as well as many other hydrocarbon compounds
that are emitted by motor vehicles, including those that are discussed
in more detail in Chapter 1 of the RIA. The emission reductions
expected from today's controls are set out in section IV.A and B of
this preamble and Chapter 2 of the RIA.
EPA believes that the emission reductions from the standards
finalized today for motor vehicles and their fuels, combined with the
standards currently in place, represent the maximum achievable
reductions of emissions from motor vehicles through the application of
technology that will be available, considering costs and the other
factors listed in section 202(l)(2). This conclusion applies whether
one considers just the compounds listed in Table 1.1-1 of the RIA, or
consider all of the compounds on the Master List of emissions, given
the breadth of EPA's current control programs and the broad groups of
emissions that many of the control technologies reduce. For example,
EPA has already taken significant steps to reduce diesel emissions from
motor vehicles (as well as other mobile sources). As explained above,
we have adopted stringent standards for on-highway diesel trucks and
buses and these standards control the air toxics emitted by these motor
vehicles to the extent feasible.
Emissions from motor vehicles can be chemically categorized as
hydrocarbons, trace elements (including metals) and a few additional
compounds containing carbon, nitrogen and/or halogens (e.g., chlorine).
For the hydrocarbons, which are the vast majority of these compounds,
we believe that with the controls finalized today, we will control the
emissions of these compounds from motor vehicles to the maximum amount
currently feasible or currently identifiable with available
information. Section V of this preamble provides more details about why
the standards represent maximum achievable reduction of hydrocarbons
from motor vehicles. Motor vehicle controls do not reduce individual
hydrocarbons selectively; instead, the maximum emission reductions are
achieved by controls on hydrocarbons as a group. There are fuel
controls that could selectively reduce individual air toxics (e.g.,
formaldehyde, acetaldehyde, 1,3-butadiene), as well as controls that
reduce hydrocarbons more generally. Section VI of this preamble
describes why the standards we are finalizing today represent the
maximum emission reductions achievable through fuel controls, after
considering the factors enumerated in section 202(l)(2) of the Clean
Air Act.
Motor vehicle emissions also contain trace elements, including
metals, which originate primarily from engine wear and impurities in
engine oil and gasoline or diesel fuel. EPA does not have authority to
regulate engine oil, and there are no feasible motor vehicle controls
to directly prevent engine wear. Nevertheless, oil consumption and
engine wear have decreased over the years, decreasing emission of
metals from these sources. Metals associated with particulate matter
will be captured in emission control systems employing a particulate
matter trap, such as will be used in heavy-duty vehicles meeting the
2007 standards. We believe that currently, particulate matter traps, in
combination with engine-out control, represent the maximum feasible
reduction of both motor vehicle particulate matter and toxic metals
present as a component of the particulate matter.
The mobile source contribution to the national inventory for metal
compounds is generally small. In fact, the emission rate for most
metals from motor vehicles is small enough that quantitative
measurement requires state-of-the art analytical techniques that are
only recently being applied to this source category. We have efforts
underway to gather information regarding trace metal emissions,
including mercury emissions, from motor vehicles (see Chapter 1 of the
RIA for more details).
A few metals and other elements are used as fuel additives. These
additives are designed to reduce the emission of regulated pollutants
either in combination with or without an emission control device (e.g.,
a passive particulate matter trap). Clean Air Act section 211 (a) and
(b) provide EPA with various authorities to require the registration of
fuel additives by their manufacturers before their introduction into
commerce. Registration involves certain data requirements that enable
EPA to identify products whose emissions may pose an unreasonable risk
to public health. In addition, this section provides EPA with authority
to require health effects testing to fill any gaps in the data that
would prevent a determination regarding the potential for risk to the
public. It is under the section 211 registration program that EPA is
currently generating the information needed to update an assessment of
the potential human health risks related to having manganese in the
national fuel supply. Clean Air Act section 211(c) provides the primary
mechanism by which EPA would take actions necessary to minimize
exposure to emissions of metals or other additives to diesel and gasoline.
Existing regulations limit sulfur in gasoline and diesel fuel to
the maximum amount feasible and will reduce emissions of all sulfur-
containing compounds (e.g., hydrogen sulfide, carbon disulfide) to the
greatest degree achievable.137 138 139 For the remaining
compounds (e.g., chlorinated

[[Page 8461]]

compounds), we currently have very little information regarding
emission rates and conditions that impact emissions. This information
would be necessary in order to evaluate potential controls under
section 202(l). Emissions of hydrocarbons containing chlorine (e.g.,
dioxins/furans) would likely be reduced with control measures that
reduce total hydrocarbons, just as these emissions were reduced with
the use of catalytic controls that lowered exhaust hydrocarbons.
---------------------------------------------------------------------------

\137\ 65 FR 6697, February 10, 2000.
\138\ 66 FR 5002, January 18, 2001.
\139\ 69 FR 38958, June 29, 2004 (standards for non-road diesel
engines and fuels). Although non-road vehicles are not ``motor
vehicles,'' and so are not subject to section 202(1)(2), EPA
nevertheless has adopted standards resulting in the greatest
feasible reductions of mobile source air toxics from these engines.
---------------------------------------------------------------------------

V. New Light-Duty Vehicle Standards

A. Introduction

The program we are establishing for vehicles will achieve the same
significant toxics reductions that we projected for the proposed rule
(see generally 71 FR 15845-15848). The program is very similar to that
proposed except for a few minor changes made in response to comments we
received. These changes will improve the implementation of the program
without significantly changing the program's overall emission
reductions and environmental benefits. As described in this section, we
are adopting stringent new nonmethane hydrocarbon standards for
vehicles to reduce hydrocarbon (HC) emissions during vehicle cold
temperature operation. As discussed in the proposal, the current HC
emissions standards are measured within a range of specified warm
temperatures, and the test procedure does not include cold
temperatures. Data indicate that cold HC emissions currently are very
high for many vehicles compared to emissions at normal test
temperatures. The new cold temperature standards and program
requirements will be phased in starting in 2010. When fully phased in,
the new standards will further reduce overall vehicle HC emissions by
about 31%, or by about 883,000 tons in 2030.
By reducing overall HC emissions from vehicles, we will be
significantly reducing several gaseous toxics including benzene,
formaldehyde, 1,3-butadiene, and acetaldehyde. We also project that the
cold temperature standard will provide concurrent reductions in direct
PM emissions from vehicles, since the strategies manufacturers are
expected to employ to reduce cold HC will reduce PM as well. Although
Clean Air Act section 202(l) deals with control of air toxics, and not
criteria pollutants like PM, this co-benefit of cold temperature
control is significant.
We are finalizing the new cold temperature standards and
implementation schedule essentially as proposed. We are also adopting
several other related provisions and requirements largely as proposed.
Many of these provisions will help the manufacturers smoothly
transition to the new standards in the shortest lead time possible.
They include corporate average emissions standards, emissions credits,
options for alternative phase-in schedules, and special provisions for
small businesses. The program also includes certification and
compliance provisions.
We are also adopting new evaporative emissions standards, beginning
in model year 2009. The new standards are essentially the same as those
contained in the California LEVII program. Manufacturers have been
selling 50-state evaporative systems that meet both the Tier 2 and
LEVII requirements. Today's final rule will ensure that industry
continues this practice.
Sections V.B. and V.C. provide the details of the new cold
temperature and evaporative emissions standards, respectively, and
briefly discuss some of the comments we received on the proposed
vehicles program. We have seriously considered all of the input from
stakeholders in developing the final vehicles program and believe that
the final rule appropriately addresses the concerns of all
stakeholders. We provide a full discussion of the comments we received
on vehicles in Chapter 3 of the Summary and Analysis of Comments for
this rule.

B. What Cold Temperature Requirements Are We Adopting?

1. Why Are We Adopting a New Cold Temperature NMHC Standard?
As emissions standards have become more stringent, manufacturers
have concentrated primarily on controlling emissions performance just
after the start of the engine in order to further reduce emissions. To
comply with stringent hydrocarbon emission standards at 75 [deg]F,
manufacturers developed new emission control strategies and practices
that resulted in significant emissions reductions at that start
temperature. We expected that proportional reductions in hydrocarbon
emissions would occur at other colder start temperatures as a result of
the more stringent standards. We believe that there is no engineering
reason why proportional control should not be occurring on a widespread
basis.
In some cases, certification data for recent model year light-duty
vehicles indicate that individual vehicles did demonstrate proportional
improvements in hydrocarbon emission results at 20 [deg]F relative to
their 75 [deg]F results, confirming our belief that proportional
control is feasible and indeed is practiced at least occasionally. One
manufacturer's certification results reflected proportional
improvements across almost its entire vehicle lines, further supporting
that proportional control is feasible. However, for most vehicles,
certification reports show a sharp rise in hydrocarbon \140\ emissions
at 20 [deg] F when compared to the reported 75 [deg] F hydrocarbon
emission levels. Any rise in hydrocarbon emissions, specifically
nonmethane hydrocarbons (NMHC), will result in proportional rise in
VOC-based air toxics.\141\ While some increase in NMHC emissions can be
expected simply due to combustion limitations of gasoline engines at
colder temperatures, the reported levels of hydrocarbon emissions seem
to indicate a significantly diminished use of hydrocarbon emissions
controls occurring at colder temperatures. Thus, although all vehicle
manufacturers have been highly successful at reducing emissions at the
test start temperature range, in general, they do not appear to be
capitalizing on NMHC emission control strategies and technologies at
lower temperatures. This is likely because compliance with hydrocarbon
standards is not required at 20 degree F temperatures. (see 71 FR at
15845.) Today's rule remedies this by requiring such compliance.
---------------------------------------------------------------------------

\140\ Most certification 20 [deg]F hydrocarbon levels are
reported as total hydrocarbon (THC), but NMHC accounts for
approximately 95% of THC as seen in results with both THC and NMHC
levels reported. This relationship also is confirmed in EPA test
programs supporting this rulemaking.
\141\ ``VOC/PM Cold Temperature Characterization and Interior Climate
Control Emissions/Fuel Economy Impact,'' Volume I and II, October 2005.
---------------------------------------------------------------------------

2. What Are the New NMHC Exhaust Emissions Standards?
We are finalizing a set of standards that will achieve proportional
NMHC control from the 75 [deg]F Tier 2 standards to the 20 [deg]F test
point. We expect that by fully utilizing available Tier 2 hardware and
software control strategies, manufacturers will be able to achieve this
standard without major changes to Tier 2 vehicle designs or the use of
additional technology. Table V.B-1 contains the final standards.

[[Page 8462]]

Table V.B-1.--20 [deg]F FTP Exhaust Emission Standards
------------------------------------------------------------------------
NMHC sales-weighted fleet
Vehicle GVWR and category average standard (grams/
mile)
------------------------------------------------------------------------
< =6000 lbs: Light-duty vehicles (LDV) & 0.3
Light light-duty trucks (LLDT)............
>6000 lbs: Heavy light-duty trucks (HLDT) 0.5
up to 8,500 lbs & Medium-duty passenger
vehicles (MDPV) up to 10,000 lbs..........
------------------------------------------------------------------------

As shown in the table, we are finalizing, as proposed, two separate
sales-weighted fleet average NMHC standards: 0.3 grams/mile for
vehicles at or below 6,000 pounds (lbs) GVWR and 0.5 grams/mile for
vehicles over 6,000 lbs, including MDPVs.\142\ NMHC emissions will be
measured during the Cold Federal Test Procedure (FTP) test, which
already requires hydrocarbon measurement.\143\ The new standard does
not require additional certification testing beyond what is required
today with ``worst case'' model selection of a durability test group.\144\
---------------------------------------------------------------------------

\142\ Tier 2 created the medium-duty passenger vehicle (MDPV)
category to include larger complete passenger vehicles, such as SUVs
and vans, with a GVWR of 8,501-10,000 pounds GVWR. Large pick-ups
above 8,500 pounds are not included in the MDPV category but are
included in the heavy-duty vehicle category.
\143\ 40 CFR Subpart C, Sec. 86.244-94 requires the measurement
of all pollutants measured over the FTP except NO_X.
\144\ The existing cold FTP test procedures are specified in 40
CFR Subpart C. In the final rule for fuel economy labeling, (71 FR
77872, December 27, 2006), EPA revised the cold FTP test protocol to
require manufacturers to run the heater and/or defroster while
conducting the cold FTP test. This had previously been an optional
provision. We do not believe this requirement will have a
significant impact on emissions.
---------------------------------------------------------------------------

The separate fleet average standards we are finalizing account for
challenges related to vehicle weight. We examined certification data
from Tier 2 and interim non-Tier 2 vehicles (i.e., vehicles not yet
phased into the final Tier 2 program, but meeting interim standards
established by Tier 2), and saw a general trend of increased
hydrocarbon levels with heavier GVWR vehicles. Some comments suggested
that the standard for HLDT/MDPVs should be the same standard as applies
to LDVs or contain a second future phase that reduces emissions to
those levels. At this time, we continue to believe that heavier
vehicles have application-specific design limitations. Heavier vehicles
generally produce higher emissions for several reasons. First, added
weight requires additional work to accelerate the vehicle mass,
generally resulting in higher emissions, particularly soon after engine
start-up. Second, the design of these emission control systems may
incorporate designs for specific duty cycles (i.e., trailer towing)
that can negatively affect emissions, particularly during 20[deg] F
cold starts. For example, since the catalyst may be located further
away from the engine for protection from high exhaust temperatures
during design-specific duty cycles, warm-up of the catalyst is
typically delayed, especially at colder temperatures. Therefore, we
believe the 0.3 g/mile fleet average standard for vehicles below 6,000
lbs GVWR is not technically feasible at this time for heavier vehicles.
We are thus finalizing a 0.5 g/mile standard for vehicles over 6000 lbs
GVWR, including both HLDTs (6000 lbs to 8500 lbs) and MDPVs.
We are finalizing the sales-weighted fleet average approach as
proposed, as the way to achieve the greatest degree of emission control
for Tier 2 vehicles. At the same time, this approach allows
manufacturers sufficient lead time and flexibility to certify different
vehicle groups to different levels, thus lowering the costs of the
program. A fleet average provides manufacturers with flexibility to
balance challenging vehicle families with ones that more easily achieve
the standards. We believe this approach is appropriate because the base
Tier 2 program is also based on emissions averaging, and will result in
a mix of emissions control strategies across the fleet that have
varying cold temperature capabilities. While the Tier 2 program
continues to phase in, manufacturers are concurrently developing
emissions control packages. The capabilities of each Tier 2 package
will not be fully understood until manufacturers are able to evaluate
the potential of the individual designs to control cold temperature
emissions.
We received several comments from state and environmental groups
supporting the new cold temperature standards. Manufacturers indicated
their support of the Agency's initiative to seek reductions in MSATs,
and one manufacturer commented that cold temperature hydrocarbon
control is both effective and logical. Manufacturers commented that the
new standards would be very challenging, but that the flexibilities
incorporated into the final rule will significantly help manufacturers
achieve the new standards. One manufacturer with a product line limited
to vehicles below 6,000 lbs GVWR suggested that the 0.3 g/mile standard
was too stringent and unreasonable based on an assessment of their
current vehicle emission levels. The manufacturer's comments did not
provide data or further technical analysis to substantiate this claim.
We know of no engineering basis for the standards not being technically
achievable. Moreover, there are about nine other manufacturers with
similar product lines exclusively below 6,000 lbs GVWR, and they did
not provide similar comments. We continue to believe that with careful
examination of existing emission control opportunities at colder
temperatures on Tier 2 compliant vehicles, especially given the lead
time provided, manufacturers will identify strategies to comply with
the new standards across their product lines.
We are establishing a Family Emissions Limit (FEL) structure in
which manufacturers will determine individual FELs for each group of
vehicles certified. These FELs are the standard for each individual
group, and are averaged on a sales-weighted basis to demonstrate
overall compliance with the fleet average standards. We are using the
FEL-based approach for the new cold temperature NMHC standards because
we believe it results in the same level of environmental benefit but
adds flexibility and leads to cost-effective compliance strategies. The
FEL approach is discussed further in section V.B.4 below.
We are applying the new cold temperature NMHC standards to light-
duty gasoline-fueled vehicles. However, diesel vehicles, alternative-
fueled vehicles, and heavy-duty vehicles will not be subject to these
standards, since we lack data on which to base standards. Section
V.B.6.a provides a detailed discussion of applicability and comments
received.
3. Feasibility of the Cold Temperature NMHC Standards
We believe the new standards will be challenging but are attainable
and provide the greatest emission reductions using technology that will
be available.

[[Page 8463]]

The feasibility assessment described below is based on our analysis of
the standard's stringency given current emission levels at
certification (considering deterioration, compliance margin, and
vehicle weight), available emission control techniques, and our own
feasibility testing. In addition, sections V.B.3-6 describe the lead
time and flexibility within the program structure, which also
contribute to the achievability of the standards. There are a number of
technologies discussed below that can be utilized to achieve these
standards. We expect that manufacturers will employ these technologies
in various combinations, which will likely vary from vehicle to vehicle
depending on a vehicle's base emission control package developed for
Tier 2 compliance. Moreover, as discussed in section V.D, due to
current Tier 2 phase-in schedules, we are not yet in a position to
evaluate fully the achievability of standards based on new technologies
that may result when Tier 2 is fully phased in in model year 2009.
Thus, we are not considering more stringent cold temperature NMHC
standards that would require the application of new technology to Tier
2 vehicles.
Chapter 8 of the RIA contains vehicle and nationwide cost
estimates, including capital and development costs. We believe the
estimated costs are reasonable and the rule is cost-effective, as shown
in section XIII, below. Given the emission control strategies currently
available, we expect manufacturers to implement these technologies
successfully without a significant impact on vehicle noise, energy
consumption, or safety factors. Although new emissions control
strategies are necessary at cold temperatures, we do not expect
fundamental Tier 2 vehicle hardware to change.
Manufacturers commented that the standards will be extremely
challenging because the standards are based on full useful life
performance and manufacturers must account for fuel quality in the
field to ensure adequate performance. Manufacturers also noted that
they must account for a host of requirements in addition to the new
cold temperature standards, including Tier 2 and SFTP standards. In
response, we understand the challenges involved in complying with the
new cold temperature standards and we are providing the essential lead
time for manufacturers to identify and resolve any related issues as
part of overall vehicle development. We are also including several
other provisions discussed below, including an averaging program,
phase-in, emissions credits, deficit carry-forward, and in-use
standards that provide manufacturers with flexibility in transitioning
to the new standards.
a. Currently Available Emission Control Technologies
We believe that the cold temperature NMHC standards for gasoline-
fueled vehicles being finalized today are challenging but attainable
with Tier 2 (i.e., existing) level emission control technologies. Our
determination of feasibility is based on the emission control hardware
and calibration strategies used today on Tier 2 vehicles. These
emission control technologies are utilized to meet the stringent Tier 2
standards for HC at the FTP temperature range of 68 [deg]F to 86
[deg]F, but are not generally used or activated at colder temperatures.
As discussed in section V.D, the standards we are finalizing today will
not force changes to Tier 2 compliance strategies. Many current engine
families already achieve emissions levels at or below the emission
standards being adopted (see RIA Chapter 5) and accomplish this through
software and calibration control technologies. However, a significant
number of engine families emit more than twice the level of the new
standards most likely because they fail to use the Tier 2 control
technologies at colder temperatures. We believe the new standards can
be met by the application of calibration and software approaches
similar to those currently used at 75 [deg]F. Although manufacturers
could use additional hardware to facilitate compliance with the new
standard, we are not projecting that they would choose to do so because
the standards can be achieved through lower-cost calibration and
software strategies. As described in section V.B.2.c, our own
feasibility testing of a vehicle over 6000 lbs GVWR achieved NMHC
reductions consistent with the standard through calibration approaches
alone.
In 2002, the European Union (EU) finalized a -7 [deg]C (20 [deg]F)
cold HC requirement.\145\ While the European standard is based on a
different drive cycle, manufacturers have developed individual
strategies to comply with this standard. When the EU implemented the
new cold HC standard in conjunction with a new 75 [deg]F standard
(Euro4), many manufacturers responded by employing National Low
Emission Vehicle (NLEV) \146\ level hardware and supplementing it with
advanced cold start emission control strategies. The EU similarly
determined that heavier weight vehicles may have duty-cycle based
design limitations and also adopted a separate unique emission standard
for these vehicles. Many manufacturers offer common vehicle models in
both European and U.S. markets. Such manufacturers can leverage
European models to transfer emission control technologies successfully
used for 20 [deg]F hydrocarbon control in Europe to their U.S. model
counterparts.
---------------------------------------------------------------------------

\145\ European Union (EU) Type VI Test (-7[deg]C) required for
new vehicle models certified as of 1/1/2002.
\146\ NLEV voluntary program introduced California low emission
cars and light-duty trucks (0-6000 lbs. GVW) into other states
beginning in 1999.
---------------------------------------------------------------------------

There are several strategies used in the vehicles that are
achieving proportional improvements in NMHC emissions at 20 [deg]F FTP.
Calibration and software strategies that can be used include lean limit
fuel strategies, fuel injection timing,\147\ elevated idle speeds,
retarded spark timing, redundant spark timing, and accelerated closed
loop times. These strategies are consistently and successfully used at
75 [deg]F to meet stringent Tier 2 standards. We expect that software
and/or calibration changes will perform as well or better than added
hardware. This is because some hardware such as the improved catalyst
system may not be usable immediately following the cold start because
it must warm-up to operate efficiently. Calibration and software
strategies that minimize emissions produced by the engine during this
period while simultaneously accelerating usage of the catalyst will be
more effective than most new hardware options. See RIA Chapter 5 for
further discussion.
---------------------------------------------------------------------------

\147\ Meyer, Robert and John B. Heywood, ``Liquid Fuel Transport
Mechanisms into the Cylinder of a Firing Port-Injected SI Engine
During Start-up,'' SAE 970865, 1997.
---------------------------------------------------------------------------

In addition to calibration strategies, some manufacturers may
comply with the new standards by extending the use of existing Tier 2
hardware to 20 [deg]F. An example of this is secondary air systems.
Several European models sold in the U.S. market demonstrate excellent
cold HC performance and utilize secondary air systems from 75 [deg]F to
20 [deg]F start temperatures. The secondary air systems reduce
emissions by injecting ambient air into the exhaust, thus supplying
oxygen for more complete combustion. This also supplies supplemental
heat to the catalyst. These systems have been used extensively to
reduce hydrocarbon emissions at 75 [deg]F starts. Currently, auto

[[Page 8464]]

makers are equipping a portion of the Tier 2 fleet with secondary air
systems for compliance with Tier 2 standards.
Some manufacturers with vehicles containing secondary air systems
claimed that they are not utilizing them at temperatures below freezing
simply because of past engineering issues. Those successfully using
secondary air at 20 [deg]F (mainly European companies) indicated that
these challenges have been addressed through design changes. The
robustness of these systems below freezing has also been confirmed with
the manufacturers and with the suppliers of the secondary air
components.\148\ While alternative technologies are available and
produce comparable results, vehicles equipped with secondary air
technology should meet the new 20 [deg]F standard by utilizing it at
colder temperatures.
---------------------------------------------------------------------------

\148\ Memo to docket ``Discussions Regarding Secondary Air
System Usage at 20[deg]F with European Automotive Manufacturers and
Suppliers of Secondary Air Systems,'' December 2005.
---------------------------------------------------------------------------

b. Feasibility Considering Current Certification Levels, Deterioration
and Compliance Margin
The standards we are finalizing will have a full useful life of
120,000 miles, consistent with Tier 2 standards. We believe the 0.3 g/
mile FEL standard leaves adequate flexibility for compliance margins
and any emissions deterioration concerns. Of the vehicles certified to
Tier 2 with available cold temperature certification data,
approximately 20% of vehicles below 6,000 lbs GVWR had HC levels in the
range of 0.18 to 0.27 g/mile, which is two to three times the 75 [deg]F
Tier 2 bin 5 full useful life standard. These reported HC levels are
from Cold CO test results for certification test vehicles with
typically only 4,000 mile aged systems, without full useful life
deterioration applied. Rapid advances in emission control hardware
technology have lowered deterioration factors used by manufacturers to
demonstrate full useful life compliance, usually indicating little or
no deterioration over a vehicle's lifetime. These deterioration factors
are common across all required test cycles including cold temperature
testing. Additionally, manufacturers typically incorporate a 20% to 30%
compliance margin to account for in-use issues that may cause emissions
variability. See RIA Chapter 5 for further discussion and details
regarding current certification levels.
c. Feasibility and Test Programs
While a few of the heavier vehicles achieved emission levels below
the 0.5 g/mile level, there are only limited 20 [deg]F certification
results for Tier 2 compliant vehicles over 6000 lbs GVWR because the
Tier 2 standards are still phasing in for these vehicles. Prior to
proposal, we conducted a feasibility study in 20 [deg]F conditions for
Tier 2 vehicles over 6000 lbs GVWR. The test program further
investigated the feasibility of compliance for heavier vehicles and
assessed their capabilities with typical Tier 2 hardware. For one
vehicle with models above and below 6,000 lbs GVWR, we reduced HC
emissions by 60-70%, depending on the control strategy. This vehicle
had a baseline level of about 1.0 g/mile. The results are well within
the 0.5 g/mile standard including compliance margin, and within a 0.3
g/mile level on some tests. We achieved these reductions through
recalibration without the use of new hardware.
Comments from the auto industry suggested that the original single
vehicle feasibility test program and the approach used to reduce
emission levels on the feasibility vehicle were too simplistic and did
not fully account for competing requirements. The commenter stated that
that Tier 2 FTP and SFTP requirements have affected hardware decisions,
such as catalyst location, and make it more difficult to simultaneously
obtain optimal performance at colder temperatures. For the final rule,
we completed a second feasibility program to help address the comments
regarding the first feasibility program. For the second feasibility
test program, we tested a vehicle with some of the specific challenges
listed by the auto industry which represented a worst case vehicle from
the perspective of cold temperature emissions control including
catalyst location and a large displacement engine. The second
feasibility program utilized emission control methods already practiced
in the production European version of the vehicle tested, helping to
demonstrate that significant emission controls through calibration are
available to manufacturers today. Simply utilizing the European
emission controls resulted in a 32% reduction in NMHC emissions. The
findings from both studies are provided in detail in the RIA.
While the auto industry did not question the feasibility of the
standards, they expressed concerns that EPA was not conveying the
complexity of effort required for full product line manufacturers to
meet the new standards. We believe that the feasibility program
demonstrated that Tier 2 vehicles, including higher weight vehicles,
currently have existing emission control capabilities to achieve the
new standards. The extensive emission data from certification tests
detailed in RIA Chapter 5 provides substantial support to the
assessment that Tier 2 vehicles generally possess the necessary
technology to achieve the new standards. In most cases, the
technologies need to be activated and optimized at colder temperatures
through calibration strategies. However, we recognize that
manufacturers, particularly full line manufacturers, will have to do
significant development work to bring their expansive Tier 2 product
line into compliance with the new standards over the vehicles' full
useful life. This is why we have included a phase-in of the standards
over 6 model years.
4. Standards Timing and Phase-In
a. Phase-In Schedule
As proposed, we will begin implementing the standard in the 2010
model year (MY) for LDV/LLDTs and 2012 MY for HLDT/MDPVs. The
implementation schedule, in Table V.B-2, begins three model years after
the Tier 2 phase-in is complete for each vehicle class. Manufacturers
will demonstrate compliance with phase-in requirements through sales
projections, similar to Tier 2, as discussed below in Section V.B.7.

Table V.B-2.--Phase-In Schedule for 20 [deg]F NMHC Standard by Model Year
----------------------------------------------------------------------------------------------------------------
Vehicle GVWR (category) 2010 2011 2012 2013 2014 2015
----------------------------------------------------------------------------------------------------------------
< =6000 lbs (LDV/LLDT)..................................... 25% 50% 75% 100% ....... .......
>6000 lbs HLDT and MDPV................................... ....... ....... 25% 50% 75% 100%
----------------------------------------------------------------------------------------------------------------

[[Page 8465]]

We requested comments on the proposed start date and duration of
the phase-in schedule. Generally, manufacturers supported the phase-in
schedule. Commenters indicated that the stringency of the standards
will increase the development workload and facility demands, but that
the proposed rule recognized these cost issues and provided sufficient
mechanisms for phase-in flexibility to help manufacturers transition to
the new program. One manufacturer with only LDV and LLDT vehicles in
their product line commented that the required phase-in percentage
affects a larger portion of their products compared with other
manufacturers with heavier vehicles, and therefore the phase-in should
be extended to accommodate construction of new facilities. Conversely,
a non-profit organization commented that EPA should begin the program
earlier than we proposed. The organization cited our assessment that
manufacturers could utilize primarily calibration and software changes,
and not hardware changes, to achieve compliance. However, as discussed
below, we believe that the finalized start date and phase-in schedule
will achieve the greatest amount of emissions reductions in the
shortest feasible amount of time.
EPA must consider lead time in determining the greatest degree of
emission reduction achievable under section 202(l) of the Clean Air
Act. Also, for vehicles above 6,000 GVWR, section 202(a) of the Act
requires that four years of lead time be provided to manufacturers. We
believe that lead time and phase-in schedule is needed to allow
manufacturers to develop compliant vehicles without significant
disruptions in their product development cycles. The three-year period
between completion of the Tier 2 phase-in and the start of the new cold
NMHC standard should provide vehicle manufacturers sufficient lead time
to design their compliance strategies and to determine the product
development plans necessary to meet the new standards.
We recognize that the new cold temperature standards we are
finalizing could represent a significant new challenge for many
manufacturers and development time will be needed. The issue of NMHC
control at cold temperatures was not anticipated by many entities, and
research and development to address the issue is consequently at a
rudimentary stage for some manufacturers. Lead time is therefore
necessary before compliance can be demonstrated. While certification
will only require one vehicle model of a durability group to be tested,
manufacturers must do development on all vehicle combinations to ensure
full compliance within the durability test group. A phase-in is needed
because manufacturers must develop control strategies for several
vehicle lines. Since manufacturers cannot be expected to implement the
standard over their entire product line in 2010, we believe a phase-in
allows the program to begin sooner than would otherwise be feasible.
As noted at proposal, the lead time and phase-in are also needed to
address test facility availability issues (see 71 FR 15849). Prior to
proposal, manufacturers raised concerns that a rapid phase-in schedule
would lead to a significant increase in the demand for their cold
testing facilities, which could necessitate substantial capital
investment in new cold test facilities to meet development needs. This
is because manufacturers would need to use their cold testing
facilities not only for certification but also for vehicle development.
Durability test groups may be large and diverse and therefore require
significant development effort and cold test facility usage for each
model. If vehicle development is compressed into too narrow a time
window, significant numbers of new facilities would be needed.
Manufacturers were also concerned that investment in new test
facilities would be stranded at the completion of the initial
development and phase-in period.
We took these concerns into consideration when drafting our
proposed rule and are finalizing the start date and phase-in as
proposed because we continue to believe they address these issues
adequately. Our finalized phase-in period accommodates test facilities
and work load concerns by distributing these fleet phase-in percentage
requirements over a four-year period for each vehicle weight category
(six years total). The staggered start dates for the phase-in schedule
between the two weight categories should further alleviate
manufacturers' burden regarding construction of new test facilities. We
recognize that some manufacturers may still determine that upgrades to
their current cold facility are needed to handle increased workload, or
that additional shifts must be added to their facility work schedules
that are not in place today. The lead time provided and the four-year
phase-in period provides needed time for vehicle manufacturers to
develop a compliance schedule that does not significantly interfere
with their future product plans. Manufacturers commented in support of
the lead time and phase in provided, commenting that these program
elements are needed to avoid high test facility costs.
b. Alternative Phase-In Schedules
We are finalizing provisions, as proposed, that allow manufacturers
to introduce vehicles earlier than required in exchange for flexibility
to make offsetting adjustments, on a one-for-one basis, to the phase-in
percentages in later years. Alternative phase-in schedules essentially
credit the manufacturer for its early or accelerated efforts and allow
the manufacturer greater flexibility in subsequent years during the
phase-in. Under these alternative schedules, manufacturers would have
to introduce vehicles that meet or surpass the NHMC average standards
before they are required to do so, or else introduce vehicles that meet
or surpass the standard in greater quantities than required.
As proposed, we are finalizing provisions allowing manufacturers to
apply for an alternative phase-in schedule that would still result in
100% phase-in by 2013 and 2015, respectively, for the lighter and
heavier weight categories. As with the primary phase-in, manufacturers
would base an alternative phase-in on their projected sales estimates.
An alternate phase-in schedule submitted by a manufacturer would be
subject to EPA approval and would need to provide the same emissions
reductions as the primary phase-in schedule. The alternative phase-in
cannot be used to delay full implementation past the last year of the
primary phase-in schedule (2013 for LDVs/LDTs and 2015 for HLDTs/MDPVs).
As proposed, this alternative phase-in schedule will be acceptable
if it passes a specific mathematical test (see 71 FR 15849). We have
designed the test to provide manufacturers a benefit from certifying to
the standards early, while ensuring that significant numbers of
vehicles are introduced during each year of the alternative phase-in
schedule. Manufacturers will multiply their percent phase-in by the
number of years the vehicles are phased in prior to the second full
phase-in year. The sum of the calculation will need to be greater than
or equal to 500, which is the sum from the primary phase-in schedule (4
x 25 + 3 x 50 + 2 x 75 + 1 x 100 = 500). For example, the equation for
LDVs/LLDTs will be as follows:

(6 x API₂₀₀₈) + (5 x API₂₀₀₉) + (4 x
API₂₀₁₀) + (3 xAPI₂₀₁₁) + (2 x
API₂₀₁₂) + (1 x API₂₀₁₃) >= 500%, where ``API''
is the anticipated

[[Page 8466]]

phase-in percentage for the referenced model year

As described above, the final sum of percentages for LDVs/LDTs must
equal or exceed 500 - the sum that results from a 25/50/75/100 percent
phase-in. For example, a 10/25/50/55/100 percent phase-in for LDVs/LDTs
that begins in 2009 will have a sum of 510 percent and is acceptable. A
10/20/40/70/100 percent phase-in that begins the same year has a sum of
490 percent and is not acceptable.
To ensure that significant numbers of compliant LDVs/LDTs are
introduced in the 2010 time frame (2012 for HLDT/MDPVs), manufacturers
would not be allowed to use alternative phase-in schedules that delay
the implementation of the requirements, even if the sum of the phase-in
percentages ultimately meets or exceeds 500. Such a situation could
occur if a manufacturer delayed implementation of its compliant
production until 2011 and began an 80/85/100 percent phase-in that year
for LDVs/LDTs. To protect against this possibility, we are finalizing,
as proposed, that for any alternative phase-in schedule, the
manufacturer's API x year factors for LDV/LLDTs from the 2010 and
earlier model years (2012 and earlier for HLDT/MDPVs) sum to at least
100. The early phase-in also encourages the early introduction of
vehicles meeting the new standard or the introduction of such vehicles
in greater quantity than required, achieving early emissions reductions.
One commenter recommended that EPA carefully consider the added
complexity of allowing alternative phase-in schedules before including
these provisions in the final rule. In response, we allowed
manufacturers the option of using similar alternative phase-ins for
Tier 2 and these provisions have not proven to be detrimental in the
implementation of the Tier 2 program. We believe the added flexibility
provided to manufacturers helps them to meet the new requirements as
soon as possible while also helping to minimize disruptions to their
product plans. These benefits offset the complexity added by the
alternative phase-in option.
Manufacturers commented that EPA should remove the requirement for
2010 to have a sum of 100 because it limits flexibility and could cause
manufacturers to run a deficit early in the program. We are retaining
this requirement as proposed, except for the option discussed in the
next paragraph. In general, this requirement ensures that manufacturers
introduce complying vehicles early in the phase-in. The alternative
phase-in is not intended to postpone introduction of compliant
vehicles; instead, it is to allow an accelerated introduction of
vehicles and to allow manufacturers the flexibility of aligning
compliance with production schedules. The commenter's suggestion of
removing the sum of 100 provision for MY 2010 and earlier vehicles
would essentially amount to delaying the program by one year. Since all
manufacturers make LDV/LDTs, the sum of 100 provision ensures that
environmental benefits are achieved as soon as possible, while the
alternative phase-in provision as a whole provides additional
flexibility to manufacturers.
As described above, we proposed an early-year requirement for
alternative phase-in schedules for HLDTs/MDPVs (see 71 FR 15850).
Similar to the LDV/LDT requirement, we proposed that the API x year
factors from the 2012 and earlier model years sum to at least 100. We
are finalizing the option of electing an HLDT/MDPV alternative phase-in
that meets the 500% criteria, including the 100% criteria for model
years 2012 and earlier, as proposed. However, based upon comments
received, we are revising this provision to allow additional
flexibilities. The comments pointed out that such a requirement would
pose significant hardship for limited-line manufacturers who produce
only a narrow range of HLDTs/MDPVs. For example, a manufacturer who
only sells one configuration in the HLDT/MDPV category would not have
the option of certifying only 25% of these vehicles in 2012. To meet
our proposed criteria, that manufacturer would have to ensure that the
model is fully compliant in 2012 (i.e., 100% of their HLDTs/MDPVs),
eliminating any flexibility for these manufacturers. To address this
concern, we are allowing HLDT/MDPV manufacturers the additional option
of employing a phase-in not meeting the early year requirement (sum of
100 in 2012) as long as their full phase-in is accelerated. Under this
option, we are requiring only that the full alternative phase-in
equation may meet or exceed 600% for HLDTs/MDPVs. We believe this will
still yield environmental benefits as quickly as possible, while not
putting an unreasonable burden on limited-line manufacturers of HLDTs/
MDPVs. Manufacturers with limited HLDT/MDPV product offerings will
still achieve 100 percent phase-in of the HLDTs/MDPVs before the end of
the phase-in schedule in 2015. For example, a manufacturer that only
has one HLDT/MDPV family and achieves 100% phase-in in 2013 would have
a sum of 600% in the equation:

(6 x 0) + (5 x 0) + (4 x 0) + (3 x 100%) + (2 x 100%) + (1 x 100%) = 600%

As noted above, phase-in schedules, in general, add little
flexibility for manufacturers with limited product offerings because a
manufacturer with only one or two test groups cannot take full
advantage of a 25/50/75/100 percent or similar phase-in. Therefore,
consistent with our proposal which reflected the recommendations of the
Small Advocacy Review Panel (SBAR Panel), which we discuss in more
detail later in section V.E, manufacturers meeting EPA's definition of
``small volume manufacturer'' will be exempt from the phase-in
schedules and will be required simply to comply with the final 100%
compliance requirement. This provision will only apply to small volume
manufacturers and not to small test groups of larger manufacturers.
5. Certification Levels
Manufacturers typically certify groupings of vehicles called
durability groups and test groups, and they have some discretion on
what vehicle models are placed in each group. A durability group is the
basic classification used by manufacturers to group vehicles to
demonstrate durability and to predict deterioration. A test group is a
basic classification within a durability group used to demonstrate
compliance with FTP 75 [deg]F standards.\149\ For Cold CO,
manufacturers certify on a durability group basis, whereas for 75
[deg]F FTP testing, manufacturers certify on a test group basis. In
keeping with the current cold CO standards, we are requiring testing on
a durability group basis for the cold temperature NMHC standard, as
proposed (see 71 FR 15850). Manufacturers will have the option of
certifying on the smaller test group basis, as is allowed under current
cold CO standards. Testing on a test group basis will require more
tests to be run by manufacturers but may provide them with more
flexibility within the averaging program. In either case, the worst-
case vehicle within the group from an NMHC emissions standpoint must be
tested for certification.
---------------------------------------------------------------------------

\149\ 40 CFR 86.1803-01.
---------------------------------------------------------------------------

For the new standard (and consistent with certification for most
section 202 standards), manufacturers will declare a family emission
limit (FEL) for each group either at, above, or below the fleet
averaging standard. The FEL must be based on the certification NMHC
level, including deterioration factor, plus the

[[Page 8467]]

compliance margin manufacturers feel is needed to ensure in-use
compliance. The FEL becomes the standard for each group, and each group
could have a different FEL so long as the projected sales-weighted
average level met the fleet average standard at time of certification.
Like the standard, the FEL will be set at one significant digit to the
right of the decimal point. Manufacturers will compute a sales-weighted
average for the NMHC emissions at the end of the model year and then
determine credits generated or needed based on how much the average is
above or below the standard.
One commenter questioned if the FEL approach would interfere with
the Tier 2 program, which uses bins rather than FELs. We do not believe
that the two approaches create a conflict because compliance with Tier
2 and the cold temperature standards operate independent of one
another. Tier 2 standards and bins are not a factor when manufacturers
demonstrate compliance with the cold temperature standards.
6. Credit Program
As described above, we are finalizing proposed provisions allowing
manufacturers to average the FELs for NMHC emissions by sales of their
vehicles and comply with a corporate average NMHC standard (see 71 FR
15850). In addition, we are finalizing, as proposed, banking and
trading provisions: when a manufacturer's average NMHC emissions from
vehicles certified and sold falls below the corporate average standard,
the manufacturer may generate credits that it could save for later use
(banking) or transfer to another manufacturer (trading). Manufacturers
must consume any credits if their corporate average NMHC emissions were
above the applicable standard for the weight class.
As proposed, credits may be generated prior to, during, and after
the phase-in period. Manufacturers could certify LDVs/LLDTs to
standards as early as the 2008 model year (2010 for HLDTs/MDPVs) and
receive early NMHC credits for their efforts. They could use credits
generated under these ``early banking'' provisions after the phase-in
begins in 2010 (2012 for HLDTs/MDPVs).
One organization opposed the use of credits from one weight class
to offset debits in another weight class. However, EPA views the
averaging, banking, and trading (ABT) provisions as an important
element in setting emission standards reflecting the greatest degree of
emission reduction achievable, considering factors including cost and
lead time. If there are vehicles that will be particularly costly or
have a particularly hard time coming into compliance with the standard,
the ABT program allows a manufacturer to adjust the compliance schedule
accordingly, without special delays or exceptions having to be written
into the rule. This is an important flexibility especially given the
current uncertainty regarding optimal technology strategies for any
given vehicle line. In these circumstances, ABT allows us to consider a
more stringent emission standard than might otherwise be achievable
under the Clean Air Act, since ABT reduces the cost and improves the
technological feasibility of achieving the standard. By enhancing the
technological feasibility and cost-effectiveness of the new standard,
ABT allows the standard to be attainable earlier than might otherwise
be possible. Also see, e.g., 69 FR 38996-97, (June 19, 2004), which
discusses an ABT program for nonroad diesel engines, which allows for
use of credits across engine families. This type of credit use can be
important in enhancing standards' overall technical feasibility, cost-
effectiveness, and pace of implementation.
a. How Credits Are Calculated
As proposed, the corporate average for each weight class will be
calculated by computing a sales-weighted average of the FEL NMHC levels
to which each group was certified. As discussed above, manufacturers
will group vehicles into durability groups or test groups and establish
an FEL for each group. This FEL becomes the standard for that group.
Consistent with FEL practices in other vehicle standards, manufacturers
may opt to select an FEL above the test level. The FEL will be used in
calculating credits. The number of credits or debits will then be
determined using the following equation:

Credits or Debits = (Standard - Sales-weighted average of FELs to
nearest tenth) x Actual Sales

If a manufacturer's average was below the 0.3 g/mi corporate
average standard for LDVs/LDTs (below 0.5 g/mi for HLDTs/MDPVs),
credits would be generated. These credits could then be used in a
future model year when its average NMHC might exceed the 0.3 or the 0.5
standard. Conversely, if the manufacturer's fleet average was above the
corporate average standard, banked credits could offset the difference,
or credits could be purchased from another manufacturer.
b. Credits Earned Prior to Primary Phase-In Schedule
As proposed, we are finalizing provisions allowing manufacturers to
earn early emissions credits if they introduce vehicles that comply
with the new standards early and the corporate average of those
vehicles is below the applicable standard. Early credits could be
earned starting in model year 2008 for vehicles meeting the 0.3 g/mile
standard and in 2010 for vehicles meeting the 0.5 g/mile standard.
These emissions credits generated before the start of the phase-in
could be used both during and after the phase-in period and have all
the same properties as credits generated by vehicles subject to the
primary phase-in schedule. As mentioned in section V.B.4.b above, we
are also finalizing a provision that allows manufacturers to apply for
an alternative phase-in schedule for vehicles that are introduced
early. The alternative phase-in and early credits provisions would
operate independent of one another.
c. How Credits Can Be Used
A manufacturer can use credits in any future year when its
corporate average is above the standard, or it can trade (transfer) the
credits to other manufacturers. Because of separate sets of standards
for the different weight categories, we are finalizing as proposed that
manufacturers compute their corporate NMHC averages separately for LDV/
LLDTs and HLDTs/MDPVs. Credit exchanges between LDVs/LLDTs and HLDTs/
MDPVs will be allowed. This will provide added flexibility for fuller-
line manufacturers who may have the greatest challenge in meeting the
new standards due to their wide disparity of vehicle types/weights and
emissions levels.
d. Discounting and Unlimited Life
Credits will allow manufacturers a way to address unexpected shifts
in their sales mix. The NMHC emission standards in this program are
quite stringent and do not present easy opportunities to generate
credits. Therefore, we will not discount unused credits. Further, the
degree to which manufacturers invest the resources to achieve extra
NMHC reductions provides true value to the manufacturer and to the
environment. We do not want to take measures to reduce the incentive
for manufacturers to bank credits, nor do we want to take measures to
encourage unnecessary credit use. Consequently, NMHC credits will not
have a credit life limit. However, credits may only be used to offset
deficits

[[Page 8468]]

accrued with respect to the new 0.3/0.5 g/mile cold temperature
standards, and cannot be used in Tier 2 or other programs.
e. Deficits Can Be Carried Forward
When a manufacturer has an NMHC deficit at the end of a model
year--that is, its corporate average NMHC level is above the required
corporate average NMHC standard--the manufacturer will be allowed to
carry that deficit forward into the next model year. To prevent
deficits from being carried forward indefinitely, we are finalizing, as
proposed, that manufacturers will not be permitted to run a deficit for
two years in a row. A deficit carry-forward may only occur after the
manufacturer used any banked credits. If the deficit still exists and
the manufacturer chooses not to, or is unable to, purchase credits, the
deficit will be carried over. At the end of that next model year, the
deficit must be covered with an appropriate number of credits that the
manufacturer generated or purchased. Any remaining deficit means that
the manufacturer is not in compliance and can be subject to an
enforcement action.
We believe that it is reasonable to provide this flexibility to
carry a deficit for one year given the uncertainties that manufacturers
face with changing market forces and consumer preferences, especially
during the introduction of new technologies. These uncertainties can
make it hard for manufacturers to accurately predict sales trends of
different vehicle models.
f. Voluntary Heavy-Duty Vehicle Credit Program
In addition to MDPV requirements in Tier 2, we also currently have
chassis-based emissions standards for other complete heavy-duty
vehicles (e.g., large pick-ups and cargo vans) above 8,500 pound GVWR.
However, these standards do not include cold temperature CO standards.
As noted below in section V.B.6.a, we did not propose to apply cold
temperature NMHC standards to heavy-duty gasoline vehicles due to a
current lack of emissions data on which to base such standards.
Accordingly, the final rule does not contain any provisions for heavy-
duty vehicle standards or credit program.
Our proposal discussed a few ideas for voluntary approaches where
manufacturers could earn credits by including heavy-duty gasoline
vehicles in the program. We only received one comment regarding a
voluntary credit program for heavy-duty gasoline vehicles. The
organization that submitted the comment opposed the creation of NMHC
credits applicable to other vehicle categories generated by reductions
from heavy-duty vehicles. In light of this lack of support, as well as
insufficient data, we are not including a heavy-duty standard or credit
program at this time. We plan to revisit the need for and feasibility
of standards as data become available.
7. Additional Vehicle Cold Temperature Standard Provisions
a. Applicability
As proposed, the new cold temperature NMHC standards apply to all
gasoline-fueled light-duty vehicles and MDPVs sold nationwide. The cold
NMHC standards do not apply to diesel vehicles, alternative-fueled
vehicles, or to the non-gasoline portion of flex fuel vehicles
(FFVs).\150\ We are finalizing as proposed that FFVs will still require
certification to the applicable cold NMHC standard, though only when
operated on gasoline. FFVs operating on ethanol are not subject to the
cold standard. When manufacturers submit their application for
certification for FFVs (such as FFVs that can run on gasoline or E85
\151\), the FFVs must have been tested using gasoline. The application
must also include a statement that either confirms the same control
strategies used with gasoline will be used when operating on ethanol,
or that identifies any differences as an Auxiliary Emission Control
Device (AECD). Again, dedicated alternative-fueled vehicles are not covered.
---------------------------------------------------------------------------

\150\ In this preamble, we use the term flex fuel vehicle (FFV)
to mean a vehicle capable of operating on two or more different fuel
types, either separately or simultaneously. Most FFVs available
today run on gasoline and ethanol mixtures. EPA regulations use the
term ``multi-fuel vehicle'' when referring to these vehicles.
\151\ E85 is a fuel mixture consisting of 85% ethanol and 15% gasoline.
---------------------------------------------------------------------------

We requested comment on standards for vehicles operating on fuels
other than gasoline. Vehicle manufacturers agreed that the cold NMHC
standards should not apply to diesels and alternative fuel vehicles,
stating that the standard would capture all but a very small percentage
of air toxics emissions from the light-duty onroad fleet. We also
received comments in support of a standard for diesel vehicles. One
organization argued that the EPA must exercise its authority to gather
the necessary data and establish a cold temperature NMHC standard for
diesel, alternative fuel, and FFVs, or explain why such standards are
not needed.
A comprehensive assessment of appropriate standards for diesel
vehicles will require a significant amount of investigation and
analysis of issues such as feasibility and costs. While we have
significant amounts of data on which to base our final standards for
light-duty gasoline vehicles, we have very little data for light-duty
diesels. Currently, diesel vehicles are not subject to the cold CO
standard, so, unlike the situation for gasoline motor vehicles where
some certification data under cold temperature conditions are
available, there is very limited data available on diesel cold
temperature emissions. Also, many manufacturers are currently in the
process of developing their diesel product offerings and the cold
temperature performance of these vehicles cannot yet be evaluated.
Therefore, at this time, the cold NMHC standards will not apply to
light-duty diesel vehicles. We will continue to evaluate data for these
vehicles as they enter the fleet and will reconsider the need for
standards. We have adopted cold temperature FTP testing for diesels as
part of the Fuel Economy Labeling rulemaking, including NMHC
measurement.\152\ These testing data would allow us to assess diesel
NMHC certification levels over time. There are sound engineering
reasons, however, to expect cold NMHC emissions for diesel vehicles to
be as low as or even lower than those required for gasoline vehicles in
the finalized standards. This is because diesel engines operate with
leaner air-fuel mixtures compared to gasoline engines. Therefore
diesels have fewer engine-out NMHC emissions due to the abundance of
oxygen and more complete combustion. A very limited amount of
confidential manufacturer-furnished information is consistent with this
engineering hypothesis.
---------------------------------------------------------------------------

\152\ ``Fuel Economy Labeling of Motor Vehicles; Revisions to
Improve Calculations of Fuel Economy Estimates,'' Final Rule, 71 FR
77872, December 27, 2006.
---------------------------------------------------------------------------

With respect to FFVs, although FFVs are currently required to
certify to the cold CO standards at 20 [deg]F while operating on
gasoline, there is no cold testing requirement for these vehicles while
operating on the alternative fuel at 20 [deg]F. There are little data
upon which to evaluate NMHC emissions when operating on alternative
fuels at cold temperatures. For FFVs operating on E85,\153\ it is
difficult to develop a reasonable standard due to a lack of fuel
specifications, testing protocols, and test data for the 20 [deg]F cold
CO cycle. Standards reflecting use of other fuels such as methanol and
natural gas pose similar uncertainty. As in the case of diesels, it
will take time to gain an

[[Page 8469]]

understanding of these other technologies in sufficient detail to
support a rulemaking. Therefore, as proposed, we are not adopting a
cold NMHC testing requirement for FFVs while operating on the non-
gasoline fuel or for alternative fuel vehicles under this final
rulemaking. However, for FFVs, we are requiring confirmation that
emission controls used when operating on gasoline are also used when
operating on the non-gasoline fuel unless a reasonable exception why
they cannot be used is declared. We will continue to investigate these
other technologies.
---------------------------------------------------------------------------

\153\ E85 is a fuel mixture consisting of 85% ethanol and 15%
gasoline typical of a summer blend of an ethanol based alternative fuel.
---------------------------------------------------------------------------

Between the proposed rule and today's final rule, we conducted an
initial emissions testing program on a limited number of FFVs operated
on several blends of gasoline and ethanol at normal test temperatures
and 20 [deg]F. \154\ These vehicles were tested on summer gasoline and
E85 under normal test temperatures and on winter gasoline and E70 \155\
at 20 [deg]F. At 20 [deg]F, HC emissions were significantly higher with
E70 fuel than with gasoline, with the HC emissions largely consisting
of unburned ethanol generated during the cold start. The reason for the
elevated HC emission levels is that during cold starts, ethanol, which
is an MSAT, does not readily burn in the combustion chamber due to its
higher boiling point (approximately 180 [deg]F). FFVs must start on the
gasoline portion of the alternative fuel, which can compose as little
as 15% of the alternative fuel. Ethanol emissions are further increased
at colder temperatures because the lower engine start temperature will
require an increasing amount of the fuel mixture to start the vehicle
and subsequently more unburned ethanol can escape the combustion
process. However, the testing also indicates significantly lower
benzene emission levels for FFVs when operating on the high ethanol
blends. Benzene was 30% to 90% lower on E85 and approximately 30% lower
on E70 compared to the levels when run on gasoline. Acetaldehyde
emissions are significantly higher with E85 relative to emissions from
gasoline-fueled vehicles, since it is a byproduct of partial (i.e.,
incomplete) ethanol combustion. In addition, some other VOC-based
toxics emissions were generally lower with the vehicles running on E85
and E70 compared with gasoline.
---------------------------------------------------------------------------

\154\ ``Flex Fuel Vehicles (FFVs) VOC/PM Cold Temperature
Characterization When Operating on Ethanol (E10, E70, E85)'' February, 2007.
\155\ E70 is a fuel mixture consisting of 70% ethanol and 30%
gasoline typical of a winter blend of an ethanol based alternative fuel.
---------------------------------------------------------------------------

There are many issues that must be resolved before we are able to
establish a cold temperature standard for FFVs when run on E85 (and E70
at cold temperatures). These include feasibility (i.e., levels that are
technically achievable), cost, test procedures, test fuel
specifications and the appropriate form of the standard. For example,
because much of the VOC emissions from FFVs operating on the high
ethanol blends at cold temperatures is unburned ethanol, we may need to
consider whether higher NMHC level would be justified or whether an
NMHC minus ethanol standard would have merit. We plan to address these
issues as part of a broader assessment of E85 emissions regulatory
issues in the future.
One organization commented that EPA must establish cold temperature
standards for heavy-duty vehicles. Since there is no 20 [deg]F cold
standard for heavy-duty vehicles, we have no data for heavy-duty
gasoline-fueled vehicles, but we would expect a range of emissions
performance similar to that of lighter gasoline-fueled trucks. Due to
the lack of test data on which to base feasibility and cost analyses,
we did not propose cold temperature NMHC standards for these vehicles.
As mentioned previously, we plan to revisit this issue when sufficient
data become available.
b. Useful Life
We are adopting the proposed requirement that the new cold
temperature standards must be met over the full useful life of the
vehicle, consistent with other emissions standards for Tier 2 vehicles.
The ``useful life'' of a vehicle means the period of use or time during
which an emission standard applies to light-duty vehicles and light-
duty trucks.\156\ Given that we expect that manufacturers will make
calibration or software changes to existing Tier 2 technologies, it is
reasonable for the new cold temperature standards to have the same
useful life as the Tier 2 standards. For LDV/LLDT, the full useful life
values will be 120,000 miles or 10 years, whichever comes first, and
for HLDT/MDPV, full useful life is 120,000 miles or 11 years, whichever
comes first.\157\ We did not receive any comments regarding these
useful life provisions.
c. High Altitude
---------------------------------------------------------------------------

\156\ 40 CFR 86.1803-01.
\157\ 40 CFR 86.1805-04.
---------------------------------------------------------------------------

We do not expect emissions to be significantly different at high
altitude due to the use of common emissions control calibrations.
Limited data submitted by a manufacturer suggest that FTP emissions
performance at high altitude generally follows sea level performance.
Furthermore, there are very limited cold temperature testing facilities
at high altitudes. Therefore, under normal circumstances, manufacturers
will not be required to submit vehicle test data for high altitude.
Instead, manufacturers will be required to submit an engineering
evaluation indicating that common calibration approaches will be
utilized at high altitude. Any deviation from sea level in emissions
control practices must be included in the auxiliary emission control
device (AECD) descriptions submitted by manufacturers at certification.
In addition, any AECD specific to high altitude must include
engineering emission data for EPA evaluation to quantify any emission
impact and validity of the AECD. We did not receive any comments
regarding these provisions relating to altitude.
d. In-Use Standards for Vehicles Produced During Phase-In
As proposed, we are finalizing provisions for an in-use standard
that is 0.1 g/mile higher than the certification FEL for any given test
group for a limited number of model years. For example, a test group
with a 0.2 g/mile FEL would have an in-use standard of 0.3 g/mile. This
would not change the FEL or averaging approaches and would only apply
in cases where EPA tests vehicles in-use to ensure emissions
compliance. Tables V.B-3 and V.B-4 provide the finalized schedule for
the availability of the in-use standards.

[[Page 8470]]

Table V.B-3.--Schedule for In-Use Standards for LDVs/LLDTs
----------------------------------------------------------------------------------------------------------------
Model year of introduction 2008 2009 2010 2011 2012 2013
----------------------------------------------------------------------------------------------------------------
Models years that the in-use standard is available for 2008 2009 2010 2011 2012 2013
carry-over test groups................................... 2009 2010 2011 2012 2013 2014
2010 2011 2012 2013 2014
2011 2012 2013
----------------------------------------------------------------------------------------------------------------

Table V.B-4.--Schedule for In-Use Standards for HLDVs/MDPVs
----------------------------------------------------------------------------------------------------------------
Model year of introduction 2010 2011 2012 2013 2014 2015
----------------------------------------------------------------------------------------------------------------
Models years that the in-use standard is available for 2010 2011 2012 2013 2014 2015
carry-over test groups................................... 2011 2012 2013 2014 2015 2016
2012 2013 2014 2015 2016
2013 2014 2015
----------------------------------------------------------------------------------------------------------------

This approach is similar to the one adopted in the Tier 2
rulemaking.\158\ As we have indicated, the standards we are finalizing
will be more challenging for some vehicles than for others. With any
new technology, or even with new calibrations of existing technology,
there are risks of in-use compliance problems that may not appear in
the certification process. In-use compliance concerns may discourage
manufacturers from applying new calibrations or technologies. Thus, we
believe it is appropriate, for the first few years, for those vehicles
most likely to require the greatest applications of effort to provide
assurance to the manufacturers that they will not face recall if they
exceed standards in use by a specified amount.
---------------------------------------------------------------------------

\158\ ``Control of Air Pollution from New Motor Vehicles: Tier 2
Motor Vehicle Emissions Standards and Gasoline Sulfur Control
Requirements,'' Final Rule, 65 FR 6796, February 10, 2000.
---------------------------------------------------------------------------

The in-use standards will be available for the first few model
years of sales after a test group meeting the new standards is
introduced, according to a schedule that provides more years for test
groups introduced earlier in the phase-in. This schedule provides
manufacturers with time to determine the in-use performance of vehicles
and learn from the earliest years of the program to help ensure that
vehicles introduced after the phase-in period meet the final standards
in-use. The in-use compliance margin only applies to carry-over models.
That is, once a test group is certified to the new standards, it will
be carried over to future model years.
We received one comment on the provisions for an interim in-use
standard. A manufacturer commented that the EPA should consider
allowing an interim in-use increment greater than 0.1 g/mi to account
for known variability in in-use conditions and vehicle technologies.
However, we did not receive any data that supported the manufacturer's
assertion, nor any indication of an acceptable increase beyond the 0.1
g/mi increment. Furthermore, no other manufacturers commented on this
provision. We believe the 0.1 g/mi increment is sufficient and that
anything greater may result in a reduction of emission control.
Therefore, the interim in-use standard is finalized as proposed.
8. Monitoring and Enforcement
As proposed, manufacturers must either report that they met the
relevant corporate average standard in their annual reports to the
Agency, or show via the use of credits that they have offset any
exceedance of the corporate average standard. Manufacturers must also
report their credit balances or deficits. EPA will monitor the program.
As in Tier 2, the averaging, banking and trading program will be
enforced through the certificate of conformity that manufacturers must
obtain in order to introduce any regulated vehicles into commerce.\159\
The certificate for each test group will require all vehicles to meet
the emissions level to which the vehicles were certified, and will be
conditioned upon the manufacturer meeting the corporate average
standard within the required time frame. If a manufacturer fails to
meet this condition, the vehicles causing the corporate average
exceedance will be considered to be not covered by the certificate of
conformity for that engine family. A manufacturer will be subject to
penalties on an individual vehicle basis for sale of vehicles not
covered by a certificate.
---------------------------------------------------------------------------

\159\ ``Control of Air Pollution from New Motor Vehicles: Tier 2
Motor Vehicle Emissions Standards and Gasoline Sulfur Control
Requirements,'' Final Rule, 65 FR 6797, February 10, 2000.
---------------------------------------------------------------------------

EPA will review the manufacturer's sales to designate the vehicles
that caused the exceedance of the corporate average standard. We will
designate as nonconforming those vehicles in those test groups with the
highest certification emission values first, continuing until we reach
a number of vehicles equal to the calculated number of noncomplying
vehicles, as determined above. In a test group where only a portion of
vehicles are deemed nonconforming, we will determine the actual
nonconforming vehicles by counting backwards from the last vehicle
produced in that test group number. Manufacturers will be liable for
penalties for each vehicle sold that is not covered by a certificate.
As proposed, we will condition certificates to enforce the
requirements that manufacturers not sell credits that they have not
generated. A manufacturer that transfers credits it does not have will
create an equivalent negative credit balance or deficit that the
manufacturer must make up by the reporting deadline for the same model
year. A credit deficit in such cases at the reporting deadline will be
a violation of the conditions under which EPA issued the certificate of
conformity. EPA will identify the nonconforming vehicles in the same
manner described above and nonconforming vehicles will not be covered
by the certificate.
In the case of a trade that resulted in a negative credit balance
that a manufacturer could not cover by the reporting deadline for the
model year in which the trade occurred, both the buyer and the seller
will be liable, except in cases involving fraud. We believe that
holding both parties liable will induce the buyer to exercise diligence
in assuring that the seller has or will be able to generate appropriate
credits and will help to ensure that inappropriate trades do not occur.
We did not propose any new compliance monitoring activities or
programs for vehicles. These vehicles will be subject to the
certification testing provisions of the CAP2000

[[Page 8471]]

rule.\160\ We are not requiring manufacturer in-use testing to verify
compliance. There is no cold CO manufacturer in-use testing requirement
today (similarly, we do not require manufacturer in-use testing for
SCO3 standards under the Supplemental Federal Test Procedures (SFTP)
program largely due to the limited availability of the test
facilities). As noted earlier, manufacturers have limited cold
temperature testing capabilities and we believe these facilities will
be needed for product development and certification testing. However,
we have the authority to conduct our own in-use testing program for
exhaust emissions to ensure that vehicles meet standards over their
full useful life. We will pursue remedial actions when substantial
numbers of properly maintained and used vehicles fail any standard in-
use. We also retain the right to conduct Selective Enforcement Auditing
of new vehicles at manufacturers' facilities.
---------------------------------------------------------------------------

\160\ 71 FR 2810, January 17, 2006.
---------------------------------------------------------------------------

The use of credits will not be permitted to address Selective
Enforcement Auditing or in-use testing failures. The enforcement of the
averaging standard will occur through the vehicle's certificate of
conformity. A manufacturer's certificate of conformity will be
conditioned upon compliance with the averaging provisions. If a
manufacturer failed to meet the corporate average standard and did not
obtain appropriate credits to cover its shortfalls in that model year
or in the subsequent model year (see deficit carry forward provision in
section V.B.5.e.), then the certificate for the affected test groups
will be void for all past, present, and future sales related to that
certificate. Manufacturers will need to track their certification
levels and sales unless they produced only vehicles certified to NMHC
levels below the standard and did not plan to bank credits. We did not
receive any comments on the provisions regarding Selective Enforcement
Auditing or conditions of certification.

C. What Evaporative Emissions Standards Are We Finalizing?

We are finalizing as proposed a set of numerically more stringent
evaporative emission standards for all light-duty vehicles, light-duty
trucks, and medium-duty passenger vehicles. The standards we are
finalizing are equivalent to California's LEV II standards, and these
standards are shown in Table V.C-1. The new standards represent about a
20 to 50 percent reduction (depending on vehicle weight class and type
of test) in the diurnal plus hot soak standards currently in place for
Tier 2 vehicles.\161\ As with the current Tier 2 evaporative emission
standards, the standards we are finalizing vary by vehicle weight
class. The increasingly higher standards for heavier weight class
vehicles account for larger vehicle sizes and fuel tanks (non-fuel and
fuel emissions).\162\
---------------------------------------------------------------------------

\161\ Diurnal emissions (or diurnal breathing losses) means
evaporative emissions as a result of daily temperature cycles or
fluctuations for successive days of parking in hot weather. Hot soak
emissions (or hot soak losses) are the evaporative emissions from a
parked vehicle immediately after turning off the hot engine. For the
evaporative emissions test procedure, diurnal and hot soak emissions
are measured in an enclosure commonly called the SHED (Sealed
Housing for Evaporative Determination).
\162\ Larger vehicles may have greater non-fuel evaporative
emissions, probably due to an increased amount of interior trim,
vehicle body surface area, and larger tires.

Table V.C-1.--Final Evaporative Emission Standards
[Grams of hydrocarbons per test]
------------------------------------------------------------------------
Supplemental 2-
Vehicle class 3-Day diurnal day diurnal
plus hot soak plus hot soak
------------------------------------------------------------------------
LDVs................................ 0.50 0.65
LLDTs............................... 0.65 0.85
HLDTs............................... 0.90 1.15
MDPVs............................... 1.00 1.25
------------------------------------------------------------------------

1. Current Controls and Feasibility of the New Standards
As described earlier, we are reducing the numerical level of the
evaporative emission standards applicable to diurnal and hot soak
emissions from light-duty vehicles and trucks by about 20 to 50
percent. These new standards are meant to be effectively the same as
the evaporative emission standards in the California LEV II program.
Although the new standards are numerically more stringent, as we
explained at proposal, we believe they are essentially equivalent to
the current Tier 2 standards because of differences in testing
requirements (see 71 FR 15854; also see section V.C.5 below for further
discussion of such test differences, e.g., test temperatures and fuel
volatilies). As discussed in the proposal, this view is supported by
manufacturers and by current industry practices. Based on this
understanding, we do not project additional VOC or air toxics
reductions from the evaporative standards we are finalizing today.\163\
Also, we do not expect additional costs since we expect that
manufacturers will continue to produce 50-state evaporative systems.
Therefore, harmonizing the federal and California LEV-II evaporative
emission standards will codify (i.e., lock in) the approach
manufacturers have already indicated they are taking for 50-state
evaporative systems.
---------------------------------------------------------------------------

\163\ U.S. EPA, Office of Air and Radiation, Update to the
Accounting for the Tier 2 and Heavy-Duty 2005/2007 Requirements in
MOBILE6, EPA420-R-03-012, September 2003.
---------------------------------------------------------------------------

We believe this action is an important step to ensure that the
federal standards reflect the lowest possible evaporative emissions,
and it also will provide states with certainty that the emissions
reductions we project to occur due to 50-state compliance strategies
will in fact occur. In addition, the new standards will assure that
manufacturers continue to use available fuel system materials to
minimize evaporative emissions.
In the proposal, we considered but did not propose more stringent
evaporative requirements contained in the partial zero-emission vehicle
(PZEV) portion of California's LEV II program. The LEV II program
includes PZEV credits for vehicles that achieve near zero emissions
(e.g., LDV evaporative emission standards for both the 2-day and 3-day
diurnal plus hot soak tests are 0.35 grams/test, which are more
stringent than the standards finalized today). State and local air
quality organizations commented that EPA should adopt the PZEV
evaporative standards. In addition, they indicated that California Air
Resources Board estimates the additional per vehicle cost

[[Page 8472]]

for a PZEV evaporative emission system to be about $10.20. They
commented that EPA should consider the introduction of a similar
standard for some vehicles. Moreover, they urged us to commit in the
final rule to pursue actions to achieve further evaporative emission
reductions in the future.
However, auto manufacturers supported the proposed evaporative
emission standards. They indicated that, as EPA tentatively concluded
in the proposed rule, it would be inappropriate for EPA to propose more
stringent standards. Manufacturers noted that PZEVs have been limited
to a small fraction of the light-duty fleet, mainly small 4-cylinder
passenger cars, and that the PZEV standard has not proven feasible
across the light-duty fleet. Furthermore, it is significantly more
costly to comply with the PZEV evaporative emission standard because of
significant modifications needed to the evaporative emission control
system and fuel system. Also, the auto manufacturers suggested that
emission benefits, if any, of the PZEV standard would be minimal.
We have decided not to set more stringent PZEV-equivalent
evaporative standards at this time. The limited PZEV vehicles available
today require additional evaporative emissions technology or hardware
(e.g., modifications to fuel tank and secondary canister) beyond what
will be needed for vehicles meeting the new standards that we are
adopting today. As we described in the proposed rule, at this time, we
need to better understand the evaporative system modifications (i.e.,
technology, costs, lead time, etc.) potentially needed across the
vehicle fleet to meet PZEV-level standards before we can fully evaluate
whether it is feasible to consider more stringent standards. For
example, at this point we cannot determine whether the PZEV
technologies could be used fleetwide or on only a limited set of
vehicles. Thus, in the near term, we lack any of the information
necessary to determine if further reductions are feasible, and if they
could be achievable considering cost, energy and safety issues.
Moreover, sufficient new information or data was not provided from
commenters on the proposed rule to close these gaps in our
understanding. However, we intend to consider more stringent
evaporative emission standards in the future.
2. Evaporative Standards Timing
As proposed, we will implement today's evaporative emission
standards in model year 2009 for LDVs/LLDTs and model year 2010 for
HLDTs/MDPVs. Many manufacturers already have begun or completed model
year 2008 certification. Thus, model year 2009 is the earliest
practical start date of new standards for LDVs/LLDTs. For HLDTs/MDPVs,
the phase-in of the existing Tier 2 evaporative emission standards ends
in model year 2009. Thus, the model year 2010 is the earliest start
date possible for HLDTs/MDPVs. As discussed earlier, since we believe
that manufacturers already meet these standards, there is no need for
additional lead time beyond the implementation dates we are finalizing.
3. Timing for Flex Fuel Vehicles
For FFVs, the phase-in schedule we are finalizing for the new
evaporative standards is somewhat different than the phase-in schedule
we proposed for these vehicles. In the proposal, we recognized that
manufacturers will need a few additional years of lead time to adjust
their evaporative systems to comply with the new evaporative emission
standards for FFVs operating on the non-gasoline fuel, typically E85
(see 71 FR 15855). The existing regulations require that FFVs or E85
vehicles (vehicles designed to operate on fuel that is 85 percent
ethanol and 15 percent gasoline) certify on both gasoline and E10 (E10
is a fuel containing 10 percent ethanol and 90 percent gasoline) for
the evaporative emissions test procedure. E10 is considered the ``worst
case'' test fuel for evaporative emissions, because it is the ethanol
blend that results in greater evaporative emissions. Thus, E10 is the
evaporative certification test fuel for E85 vehicles. Thus far, only a
few FFV systems have been certified to California LEV-II standards on
E10 fuel. Vehicles not certified with E10 in California are sold as
gasoline-fueled only vehicles rather than FFVs. Some manufacturers are
still developing FFVs for future introduction and the evaporative
control systems in some cases have not been fully field tested and
certified on the E10 fuel. Therefore, certifying FFVs to the new
standards on the E10 fuel (which is required by Tier 2) represents a
new requirement for manufacturers.
We proposed that FFVs would need to meet the new evaporative
emission certification standards on the non-gasoline fuel beginning in
the fourth year of the program--2012 for LDVs/LLDTs and 2013 for HLDTs/
MDPVs. We proposed that the evaporative emission standards would be
implemented in 2009 for LDVs/LLDTs and 2010 for HLDTs/MDPVs for the
FFVs when run on gasoline (along with gasoline vehicles that are not
flex fuel). At the time of proposal, we believed this additional three
years of lead time would provide sufficient time for manufacturers to
make adjustments to their new evaporative systems for FFVs, which are
limited product lines.
Auto manufacturers commented that additional lead time and
flexibility beyond that proposed is needed for the non-gasoline portion
of FFVs. Manufacturers requested the following revisions to the
proposed timing of the new evaporative emission standards for the non-
gasoline portion of FFVs:

--combine the LDV/LLDT and HLDT/MDPV fleets,
--implement the phase-in of this combined fleet starting in 2013, and
--permit a three-year phase-in of 30 percent/60 percent/100 percent for
this combined fleet.

The auto industry indicated that for many manufacturers of FFVs,
the new standards are considered new emission requirements for their
FFVs. This is unlike the situation for gasoline vehicles, where EPA
intends to codify what is already being done in practice rather than
imposing any new requirements on gasoline vehicles. For most
manufacturers of FFVs, there is no demonstrated capability at this time
to meet the new evaporative emission standards from which to begin
planning compliance to the new standards. Also, manufacturers expressed
that there are important enough differences between fuels in the
gasoline and FFVs (or the non-gasoline portion of FFVs) that
independent evaluations of FFVs on gasoline and the non-gasoline fuel
are warranted.
In addition, auto manufacturers stated that as interest in
alternative fuels has increased due to energy supply concerns, they are
suddenly considering widespread introduction of FFV models, across
entire product lines. What was at first a limited offering of a few
models may become more offerings across a manufacturer's full line of
products in the timeframe of this rulemaking. The auto industry argues
that these new developments justify lead time provisions commensurate
with those when a new emission requirement applies across a
manufacturer's light-duty product line.
They also indicated that model renewals provide the most cost-
effective timing for the introduction of new emissions capability to
meet the new standards. At this time, some manufacturers plan model
renewals for multiple vehicle lines from model years 2013 to 2015.
Allowing a three-year phase-in for the non-gasoline portion of FFVs
provides more opportunities for scheduled model renewals to coincide

[[Page 8473]]

with implementation dates for the new standards. Planning, engineering,
and development activities needed to meet these new standards can be
incorporated into the model redesign activities.
We believe that many of the concerns presented by manufacturers
supporting additional lead time are valid. Most manufacturers have less
experience meeting the new standards on the non-gasoline portion of
FFVs compared to gasoline vehicles. The new standards will apply
beginning in model year 2012 with a three-year phase-in, 30/60/100
percent, for LDVs/LLDTs and HLDTs/MDPVs grouped together (see Table
V.C-2). Although auto manufacturers requested a start date of 2013 for
a combined fleet, we believe the additional flexibilities we are
providing (three-year phase-in and grouping LDVs/LLDTs and HLDTs/MDPVs
together) is sufficient flexibility for the production of FFVs. There
is enough time between now and the implementation dates or phase-in
schedule (2012 through 2014) for manufacturers to coordinate model
renewals with the introduction of broader product offerings of FFVs.
See the Summary and Analysis of Comments of this rulemaking for further
discussion of comments and our responses to comments.

Table V.C-2.--Phase-in Schedule for Non-Gasoline Portion of FFVs: Evaporative Emission Standards*
----------------------------------------------------------------------------------------------------------------
Vehicle GVWR (Category) 2012 2013 2014
----------------------------------------------------------------------------------------------------------------
<=6000 lbs (LDVs/LLDTs) and > 6000 lbs (HLDTs and MDPVs)........ 30% 60% 100%
----------------------------------------------------------------------------------------------------------------
*Phase-in schedules are grouped together for LDVs/LLDTs and HLDTs/MDPVs.

Provisions for in-use evaporative emission standards similar to
those described below in section V.C.4 do not apply to the non-gasoline
portion of FFVs. We believe that three to five additional years to
prepare vehicles (or evaporative families) to meet the certification
standards, and to simultaneously make vehicle adjustments from the
federal in-use experience of other vehicles (including those that are
not FFVs) is sufficient to resolve any issues for FFVs. Also, we did
not receive comments requesting additional flexibility beyond the
phase-in schedule for certification vehicles discussed earlier.
Therefore, we are finalizing our proposal not to provide additional in-
use compliance margin to FFVs. According to the phase-in schedule for a
combined fleet in Table V.C-2, the evaporative emission standards will
apply both for certification and in-use beginning in 2012 for LDVs/
LLDTs and HLDTs/MDPVs.
4. In-Use Evaporative Emission Standards
As described earlier in this section, we are adopting evaporative
emission standards that are equivalent to California's LEV II
standards. Currently, the Tier 2 evaporative emission standards are the
same for certification and in-use vehicles. However, the California LEV
II program permits manufacturers to meet less stringent standards in-
use for a short time in order to account for potential variability in-
use during the initial years of the program when technical issues are
most likely to arise.\164\ The LEV II program specifies that in-use
evaporative emission standards of 1.75 times the certification
standards will apply for the first three model years after an
evaporative family is first certified to the LEV II standards (only for
vehicles introduced prior to model year 2007, the year after 100
percent phase-in).165 166 An interim three-year period was
considered sufficient to accommodate any technical issues that may arise.
---------------------------------------------------------------------------

\164\ California Air Resources Board, ``LEV II'' and ``CAP
2000'' Amendments to the California Exhaust and Evaporative Emission
Standards and Test Procedures for Passenger Cars, Light-Duty Trucks
and Medium-Duty Vehicles, and to the Evaporative Emission
Requirements for Heavy-Duty Vehicles, Final Statement of Reasons,
September 1999.
\165\ 1.75 times the 3-day diurnal plus hot soak and 2-day
diurnal plus hot soak standards.
\166\ For example, evaporative families first certified to LEV
II standards in the 2005 model year shall meet in-use standards of
1.75 times the evaporative certification standards for 2005, 2006,
and 2007 model year vehicles.
---------------------------------------------------------------------------

Federal in-use conditions may raise unique issues (e.g., salt/ice
exposure) for evaporative systems certified to the new standards (which
are equivalent to the LEV II standards), and thus, we will adopt a
similar, interim in-use compliance provision for vehicles subject to
these new federal standards. As with the LEV II program, this provision
will enable manufacturers to make adjustments for unforeseen problems
that may occur in-use during the first three years of a new evaporative
family. We believe that a three-year period is enough time to resolve
these problems, because it allows manufacturers to gain real world
experience and to make adjustments to a vehicle within a typical
product cycle.
Depending on the vehicle weight class and type of test, the Tier 2
certification standards are 1.3 to 1.9 times the LEV II certification
standards. On average the Tier 2 standards are 1.51 times the LEV II
certification standards. Thus, to maintain the same level of stringency
for the in-use evaporative emission standards provided by the Tier 2
program, we will apply the Tier 2 standards in-use for only the first
three model years after an evaporative family is first certified under
today's new standards, instead of using the LEV II 1.75 multiplier
approach described above. Since the new evaporative emission
certification standards (equivalent to LEV II standards) will be
implemented in model year 2009 for LDVs/LLDTs and model year 2010 for
HLDTs/MDPVs, these same certification standards will apply in-use
beginning in model year 2012 for LDVs/LLDTs and model year 2013 for
HLDTs/MDPVs.\167\ The schedule for in-use evaporative emissions
standards are shown in Tables V.C.-3 and V.C.-4 below.
---------------------------------------------------------------------------

\167\ For example, evaporative families first certified to the
new LDV/LLDT evaporative emission standards in the 2011 model year
will be required to meet the Tier 2 LDV/LLDT evaporative emission
standards in-use for 2011, 2012, and 2013 model year vehicles
(applying Tier 2 standards in-use will be limited to the first three
years after introduction of a vehicle), and 2014 and later model
year vehicles of such evaporative families will be required to meet
the new LDV/LLDT evaporative emission standards in-use.

Table V.C-3.--Schedule for In-Use Evaporative Emission Standards for LDVs/LLDTs
----------------------------------------------------------------------------------------------------------------
Model year of introduction 2009 2010 2011
----------------------------------------------------------------------------------------------------------------
Models Years That Tier 2 2009 2010 2011

[[Page 8474]]

Standards Apply to In-use Vehicles.............................. 2010 2011 2012
2011 2012 2013
----------------------------------------------------------------------------------------------------------------

Table V.C-4.--Schedule for In-Use Evaporative Emission Standards for HLDTs/MDPVs
----------------------------------------------------------------------------------------------------------------
Model year of introduction 2010 2011 2012
----------------------------------------------------------------------------------------------------------------
Models Years That Tier 2 Standards Apply to In-use Vehicles..... 2010 2011 2012
2011 2012 2013
2012 2013 2014
----------------------------------------------------------------------------------------------------------------

5. Existing Differences Between California and Federal Evaporative
Emission Test Procedures
As described above, the levels of the California LEV II evaporative
emission standards are seemingly more stringent than EPA's Tier 2
standards, but due to differences in California and EPA evaporative
test requirements, EPA and most manufacturers view the programs as
similar in stringency. The Tier 2 evaporative program requires
manufacturers to certify the durability of their evaporative emission
systems using a fuel containing the maximum allowable concentration of
alcohols (highest alcohol level allowed by EPA in the fuel on which the
vehicle is intended to operate, i.e., a ``worst case'' test fuel).
Under current requirements, this fuel would be about 10 percent ethanol
by volume.\168\ We are retaining these Tier 2 durability requirements
for the new evaporative emissions program. California does not require
this provision. To compensate for the increased vulnerability of system
components to alcohol fuel, manufacturers have indicated that they will
produce a more durable evaporative emission system than the Tier 2
numerical standards would imply, using the same low permeability hoses
and low loss connections and seals planned for California LEV II vehicles.
---------------------------------------------------------------------------

\168\ Manufacturers are required to develop deterioration
factors using a fuel that contains the highest legal quantity of
ethanol available in the U.S.
---------------------------------------------------------------------------

As shown in Table V.C-3, in addition to the maximum alcohol fuel
content for durability testing, the other key differences between the
federal and California test requirements are fuel volatilities, diurnal
temperature cycles, and running loss test temperatures.\169\ The EPA
fuel volatility requirement is 2 psi greater than that of California.
The high end of EPA's diurnal temperature range is 9[deg] F lower than
that of California. Also, EPA's running loss temperature is 10[deg] F
lower than California's.
---------------------------------------------------------------------------

\169\ Running loss emissions means evaporative emissions as a
result of sustained vehicle operation (average trip in an urban
area) on a hot day. The running loss test requirement is part of the
3-day diurnal plus hot soak test sequence.

Table V.C-3.--Differences in Tier 2 and LEV II Evaporative Emission Test
Requirements
------------------------------------------------------------------------
EPA California
Test Requirement Tier 2 LEV II
------------------------------------------------------------------------
Fuel volatility (Reid Vapor Pressure in psi):..... 9 7
Diurnal temperature cycle (degrees F):............ 72-96 65-105
Running loss test temperature (degrees F):........ 95 105
------------------------------------------------------------------------

Currently, California accepts evaporative emission results
generated on the federal test procedure (using federal test fuel),
because available data indicates the federal procedure to be a ``worst
case'' procedure. In addition, manufacturers can currently obtain
federal evaporative certification based upon California results
(meeting LEV II standards under California fuels and test conditions),
if they obtain advance approval from EPA.\170\
---------------------------------------------------------------------------

\170\ Currently, EPA may require comparative data from both
federal and California tests.
---------------------------------------------------------------------------

Auto manufacturers commented that meeting the new standards can be
achieved more effectively if they are provided greater flexibility in
the certification process. They recommended that EPA allow federal
evaporative certification to the new standards, which are equivalent to
California's LEV II standards, through California evaporative testing
results without obtaining advance approval. Since we are harmonizing
federal evaporative standards with the LEV II evaporative emission
standards in today's rule, we believe that for the new standards it is
unnecessary to continue to require this advance approval for California
results. Thus, we are finalizing provisions that would allow
certification to the new evaporative emission standards in accordance
with California test conditions and test procedures without pre-
approval from EPA.

D. Additional Exhaust Control Under Normal Conditions

We received comments recommending that EPA harmonize exhaust
emissions standards with the California LEV II program. We also
received comments from manufacturers stating that more stringent
tailpipe standards beyond Tier 2 were not warranted and that the
difference between Tier 2 and LEV II would not be meaningful. As
discussed in the proposal (71 FR 15856), we did not propose to further
align the federal light-duty exhaust emissions control program with
that of California. We continue to believe, for reasons discussed
below, that it would not be appropriate to adopt more stringent
tailpipe standards under normal test conditions beyond those contained
in Tier 2. It is possible that a future evaluation could result in EPA
reconsidering the option of harmonizing the Tier 2 program with
California's LEV-II program or otherwise seeking emission reductions
beyond those of the Tier 2 program and those being finalized
today.\171\ A full analysis of the comments is available in the Summary
and Analysis of Comments document for this final rule.
---------------------------------------------------------------------------

\171\ See Sierra Club v. EPA, 325 F. 3d at 480 (EPA can
reasonably determine that no further reductions in MSATs are
presently achievable due to uncertainties created by other recently
promulgated regulatory provisions applicable to the same vehicles).
---------------------------------------------------------------------------

As explained earlier, section 202(l)(2) requires EPA to adopt
regulations that contain standards which reflect the greatest degree of
emissions reductions achievable through the application of technology
that will be available, taking into consideration existing motor

[[Page 8475]]

vehicle standards, the availability and costs of the technology, and
noise, energy and safety factors. The cold temperature NMHC program
finalized today is appropriate under section 202(l)(2) as a near-term
control: that is, a control that can be implemented relatively soon and
without disruption to the existing vehicle emissions control program.
We did not propose additional long-term controls (i.e., controls that
require longer lead time to implement) because we lack the information
necessary to assess their appropriateness. We believe it will be
important to address the appropriateness of further MSAT controls in
the context of compliance with other significant vehicle emissions
regulations (discussed below).
In the late 1990's both the EPA and the California Air Resources
Board finalized new and technologically challenging light-duty vehicle/
truck emission control programs. The EPA Tier 2 program focuses on
reducing NO_X emissions from the light-duty fleet. In
contrast, the California LEV-II program focuses primarily on reducing
hydrocarbons by tightening the light-duty nonmethane organic gas (NMOG)
standards.\172\ Both programs will require the use of hardware and
emission control strategies not used in the fleet under previously
existing programs. Both programs will achieve significant reductions in
emissions. Taken as a whole, the Tier 2 program presents the
manufacturers with significant engineering challenges in the coming
years. Manufacturers must bring essentially all passenger vehicles
under the same emission control program regardless of their size,
weight, and application. The Tier 2 program represents a comprehensive,
integrated package of exhaust, evaporative, and fuel quality standards
which will achieve significant reductions in NMHC, NO_X, and
PM emissions from all light-duty vehicles in the program. These
reductions will include significant reductions in MSATs. Emission
control in the Tier 2 program will be based on the widespread
implementation of advanced catalyst and related control system
technology. The standards are very stringent and will require
manufacturers to make full use of nearly all available emission control
technologies.
---------------------------------------------------------------------------

\172\ NMOG includes emissions of nonmethane hydrocarbons plus
all other nonmethane organic air pollutants (for example,
aldehydes), which are ozone precursors. For gasoline and diesel
vehicles, NMHC and NMOG emissions levels are very similar.
---------------------------------------------------------------------------

Today, the Tier 2 program remains in its phase-in. Cars and lighter
trucks will be fully phased into the program with the 2007 model year,
and the heavier trucks won't be fully entered into the program until
the 2009 model year. Even though the lighter vehicles will be fully
phased in by 2007, we expect the characteristics of this segment of the
fleet to remain in a state of transition at least through 2009, because
manufacturers will be making adjustments to their fleets as the larger
trucks phase in. The Tier 2 program is designed to enable vehicles
certified to the LEV-II program to cross over to the federal Tier 2
program. At this point in time, however, it is difficult to predict the
degree to which this will occur. The fleetwide NMOG levels of the Tier
2 program will ultimately be affected by the manner in which LEV-II
vehicles are certified within the Tier 2 bin structure, and vice versa.
We intend to carefully assess these two programs as they evolve and
periodically evaluate the relative emission reductions and the
integration of the two programs.
Today's final rule addresses toxics emissions from vehicles
operating at cold temperatures. The technology to achieve this is
already available and we project that compliance will not be costly.
However, we do not believe that we could reasonably propose further
controls at this time. There is enough uncertainty regarding the
interaction of the Tier 2 and LEV-II programs to make it difficult to
evaluate today what might be achievable in the future. Depending on the
assumptions one makes, the LEV-II and Tier 2 programs may or may not
achieve very similar NMOG emission levels. Therefore, the eventual Tier
2 baseline technologies and emissions upon which new standards would
necessarily be based are not known today. Additionally, we believe it
is important for manufacturers to focus in the near term on developing
and implementing robust technological responses to the Tier 2 program
without the distraction or disruption that could result from changing
the program in the midst of its phase-in. We believe that it may be
feasible in the longer term to seek additional emission reductions from
the base Tier 2 program, and the next several years will allow an
evaluation based on facts rather than assumptions. For these reasons,
we are deferring a decision on seeking additional NMOG reductions from
the base Tier 2 program.

E. Vehicle Provisions for Small Volume Manufacturers

Before issuing a proposal for this rulemaking, we analyzed the
potential impacts of these regulations on small entities. As a part of
this analysis, we convened a Small Business Advocacy Review Panel (SBAR
Panel, or ``the Panel''). During the Panel process, we gathered
information and recommendations from Small Entity Representatives
(SERs) on how to reduce the impact of the rule on small entities, and
those comments are detailed in the Final Panel Report which is located
in the public record for this rulemaking (Docket EPA-HQ-OAR-2005-0036).
Based on these comments, we proposed lead time transition and hardship
provisions that will be applicable to small volume manufacturers as
described below in section V.E.1 and V.E.2. For further discussion of
the Panel process, see section XII.C of this rule and/or the Final
Panel Report. We received no comments on this section in response to
the proposed rulemaking.
As discussed in more detail in section XII.C, in addition to the
major vehicle manufacturers, three distinct categories of businesses
relating to highway light-duty vehicles would be covered by the new
vehicle standards: small volume manufacturers (SVMs), independent
commercial importers (ICIs),\173\ and alternative fuel vehicle
converters.\174\ We define small volume manufacturers as those with
total U.S. sales less than 15,000 vehicles per year, and this status
allows vehicle models to be certified under a slightly simpler
certification process. For certification purposes, SVMs include ICIs
and alternative fuel vehicle converters since they sell less than
15,000 vehicles per year.
---------------------------------------------------------------------------

\173\ ICIs are companies that hold a Certificate (or
certificates) of Conformity permitting them to import nonconforming
vehicles and to modify these vehicles to meet U.S. emission standards.
\174\ Alternative fuel vehicle converters are businesses that
convert gasoline or diesel vehicles to operate on alternative fuel
(e.g., compressed natural gas), and converters must seek a
certificate for all of their vehicle models.
---------------------------------------------------------------------------

About 34 out of 50 entities that certify vehicles are SVMs, and the
Panel identified 21 of these 34 SVMs that are small businesses as
defined by the Small Business Administration criteria (5 manufacturers,
10 ICIs, and 6 converters). Since a majority of the SVMs are small
businesses and all SVMs have similar characteristics as described below
in section V.E.1, the Panel recommended that we apply the lead time
transition and hardship provisions to all SVMs. These manufacturers
represent just a fraction of one percent of the light-duty vehicle and
light-duty truck sales. Our final rule today is consistent with the
Panel's recommendation.

[[Page 8476]]

1. Lead Time Transition Provisions
In these types of vehicle businesses, predicting sales is difficult
and it is often necessary to rely on other entities for technology (see
earlier discussions in section V on technology needed to meet the new
standards).175 176 Moreover, percentage phase-in
requirements pose a dilemma for an entity such as an SVM that has a
limited product line. For example, it is challenging for an SVM to
address percentage phase-in requirements if the manufacturer makes
vehicles in only one or two test groups. Because of its very limited
product lines, a SVM could be required to certify all their vehicles to
the new standards in the first year of the phase-in period, whereas a
full-line manufacturer (or major manufacturer) could utilize all four
years of the phase-in. Thus, similar to the flexibility provisions
implemented in the Tier 2 rule, the Panel recommended that we allow
SVMs (includes all vehicle small entities that would be affected by
this rule, which are the majority of SVMs) the following options for
meeting cold temperature NMHC standards and evaporative emission
standards as an element of determining appropriate lead time for these
entities to comply with the standards.
---------------------------------------------------------------------------

\175\ For example, as described later in section V.E.3, ICIs may
not be able to predict their sales because they are dependent upon
vehicles brought to them by individuals attempting to import
uncertified vehicles.
\176\ SMVs (those with sales less than 15,000 vehicles per year)
include ICIs, alternative fuel vehicle converters, companies that
produce specialty vehicles by modifying vehicles produced by others,
and companies that produce small quantities of their own vehicles,
but rely on major manufacturers for engines and other vital emission
related components.
---------------------------------------------------------------------------

For cold NMHC standards, the Panel recommended that SVMs simply
comply with the standards with 100 percent of their vehicles during the
last year of the four-year phase-in period. Since these entities could
need additional lead time and the new standards for LDVs and LLDTs
would begin in model year 2010 and would end in model year 2013 (25%,
50%, 75%, 100% phase-in over four years), we are finalizing, as
proposed, a provision requiring only that SVMs certify 100 percent of
their LDVs and LLDTs in model year 2013. Also, since the new standard
for HLDTs and MDPVs would start in 2012 (25%, 50%, 75%, 100% phase-in
over four years), we are finalizing, again as proposed, a provision
requiring that the SVMs certify 100 percent of their HLDTs and MDPVs in
model year 2015.
In regard to evaporative emission standards, the Panel recommended
that since the new evaporative emissions standards would not have
phase-in years, we allow SVMs to simply comply with standards during
the third year of the program. We have implemented similar provisions
in past rulemakings. Given the additional challenges that SVMs face, as
noted above, we believe that this recommendation is reasonable.
Therefore, for a 2009 model year start date for LDVs and LLDTs, we are
finalizing, as proposed, a provision requiring that SVMs meet the
evaporative emission standards in model year 2011. For a model year
2010 implementation date for HLDTs and MDPVs, we are finalizing the
proposed provision requiring that SVMs comply in model year 2012.
2. Hardship Provisions
In addition, the Panel recommended that case-by-case hardship
provisions be extended to SVMs for the cold temperature NMHC and
evaporative emission standards as an aspect of determining the greatest
emission reductions feasible. These entities could, on a case-by-case
basis, face hardship more than major manufacturers (manufacturers with
sales of 15,000 vehicles or more per year), and we are finalizing as
proposed this provision to provide what could prove to be a needed
safety valve for these entities. SVMs will be allowed to apply for up
to an additional 2 years to meet the 100 percent phase-in requirements
for cold NMHC and the delayed requirement for evaporative emissions. As
with hardship provisions for the Tier 2 rule, we are finalizing, as
proposed, a provision providing that applications for such hardship
relief must be made in writing, must be submitted before the earliest
date of noncompliance, must include evidence that the noncompliance
will occur despite the manufacturer's best efforts to comply, and must
include evidence that severe economic hardship will be faced by the
company if the relief is not granted.
We will work with the applicant to ensure that all other remedies
available under this rule are exhausted before granting additional
relief. To avoid any perception that the existence of the hardship
provision could prompt SVMs to delay development, acquisition and
application of new technology, we want to make clear that we expect
this provision to be rarely invoked, and that relief would rarely be
granted. Today's rule contains numerous flexibilities for all
manufacturers and it delays implementation dates for SVMs. We would
expect SVMs to prepare for the applicable implementation dates in
today's rule.
3. Special Provisions for Independent Commercial Importers (ICIs)
Although the SBAR panel did not specifically recommend it, we are
finalizing as proposed provisions allowing ICIs to participate in the
averaging, banking, and trading program for cold temperature NMHC fleet
average standards (as described in Table IV.B.-1), but with appropriate
constraints to ensure that fleet averages will be met. The existing
regulations for ICIs specifically prohibit ICIs from participating in
emission-related averaging, banking, and trading programs unless
specific exceptions are provided (see 40 CFR 85.1515(d)). The concern
is that they may not be able to predict their sales and control their
fleet average emissions because they are dependent upon vehicles
brought to them by individuals attempting to import uncertified
vehicles. However, an exception for ICIs to participate in an
averaging, banking, and trading program was made for the Tier 2
NO_X fleet average standards (65 FR 6794, February 10, 2000),
and today we are finalizing, as proposed, a similar exception for the
cold temperature NMHC fleet average standards.
If an ICI is able to purchase credits or to certify a test group to
a family emission level (FEL) below the applicable cold temperature
NMHC fleet average standard, the rule allows the ICI to bank credits
for future use. Where an ICI desires to certify a test group to a FEL
above the applicable fleet average standard, the rule allows them to do
so if they have adequate and appropriate credits. Where an ICI desires
to certify to an FEL above the fleet average standard and does not have
adequate or appropriate credits to offset the vehicles, we will permit
the manufacturer to obtain a certificate for vehicles using such a FEL,
but will condition the certificate such that the manufacturer can only
produce vehicles if it first obtains credits from other manufacturers
or from other vehicles certified to a FEL lower than the fleet average
standard during that model year.
Our experience over the years through certification indicates that
the nature of the ICI business is such that these companies cannot
predict or estimate their sales of various vehicles well. Therefore, we
do not have confidence in their ability to certify compliance under a
program that will allow them leeway to produce some vehicles to a
higher FEL now but sell vehicles with lower FELs later, such that they
were able to

[[Continued on page 8477]]

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